Unable to flash firmware (ASUS or Tomato) on RT-N66U (Bricked?)

[trauco]

Hi,

I'm having trouble flashing my RT-N66U, either with Tomato (which is what I want) or even returning back to the stock ASUS firmware. I believe the steps below are the correct ones to do this, but please let me know if I'm missing something:

Computer: Windows 7 with firewall and antivirus off.

- Download and install firmware recovery utility from ASUS.
- Tomato Firmware: Release 112, 64K, AIO: http://tomato.groov.pl/download/K26RT-N/build5x-112-EN/Asus RT-N66u 64k/
- Download Stock firmware for this router found on ASUS support site.

1.- Set up a static IP address (192.168.1.2) and Gateway (255.255.255.0) for the LAN interface. Disable the Wireless interface for good measure.

2.- Turn on the router while pressing the reset button. Wait a few seconds until the power LED is flashing slowly.

3a.- From the recovery utility with the the tomato/asus firmware, press upload.

Here, the utility correctly uploads the firmware (one thing I noticed is that it did not complain about the tomato firmware being incompatible as I read in several forums), and then it runs through a ~10 min progress bar that reads "System recovery in progress...". By this point, the power led is no longer flashing.

This process ends and then the process fails with "Failed to connect to wireless router. Check if the router's power LED is blinking, which denotes that the router is in rescue mode."

3b. Alternatively, visit 192.168.1.1 and try to upload the file (tomato or ASUS) using the web interface. I can do this with no issues, and the file is uploaded, but then a page saying the router will reboot and to wait a few moments shows up. I've waited 30 minutes and no reboot.

If after 3a or 3b I try to power cycle the router, it simply goes into repair mode (or it looks that way as the power led is flashing on/off). I can always go into the CFE webserver and/or ping the router, but nothing else.

I want to note this is the second unit I try, as the previous one had the same symptoms and I thought it was faulty. I'm now thinking I'm doing something wrong.

Any ideas?

 

[jlake]

The only thing I can think of is you are trying to upload the zipped file.

Try a different computer and see if that helps.

Try resetting the router to factory defaults. Press and hold the WPS button for 10 seconds while powering on.

 

[trauco]

Hi Jlake,

Thanks. I'm definitely not uploading the zip file.

 

[jlake]

yeah I re-read your post....that wouldn't be it.

Try resetting the router to factory defaults. Press and hold the WPS button for 10 seconds while powering on the router. Make sure you don't have anything else connected to the router (except you computer).

 

[trauco]

Hi,

the above finally worked. I'm not sure why, but I tried one more time and after waiting just ~20 minutes it worked, meaning it rebooted and had tomato loaded.

 

[jlake]

Yeah I've only partially bricked a router once (several years ago) and that was due to a lack of patience on my part.

 

[trauco]

Yeah, I had waited 30+ minutes before. As often happens, the problem is solves pretty much as soon as I go to the internet for help.

Thanks!

 

[TonyH]

Hi,
Machine does not lie, human fingers can. I bet you were doing something not even realizing
it. Why a healthy router won't flash?, come to think of it.

 

[mikeg]

As a matter of fact I have had the same problem with a brand new N66U bought at Amazon. I could not update the Asus F7w or Merlins f/w and as a last resort I tried to upgrade to Tomato USB Shibby f/w .109 and after 2 or 3 retries I had updated the f/w. It is not the hands or fingers what is the issue here : it is how stubborn and patience you are which gets reults.

Hi,
Machine does not lie, human fingers can. I bet you were doing something not even realizing
it. Why a healthy router won't flash?, come to think of it.

 

[csrihari]

Hey trauco,
I saw your reply to my message on the other thread. Good to see you finally got it working. I had the same message on recovery as you did but mine never recovered from that (tried recovering five times at least with stock fw). I've got my second unit and from your experience it looks like persistence might pay off. I am still reluctant to update my new unit but I have hope from your experience.

Yeah, I had waited 30+ minutes before. As often happens, the problem is solves pretty much as soon as I go to the internet for help.

Thanks!

 

[RMerlin]

A few notes:

1) If this is a brand new RT-N66U, make sure you check what hardware revision it is. The new revision B2 requires special support from the firmware to work. That means the FW must be Asuswrt 272 or newer, Asuswrt 372 or newer, Asuswrt-Merlin 372.30_2 or newer, or Shibby 112. Victek recently implemented support for the new flash as well in one of his very last betas, and I don't think Toastman has made any release yet with support for the new flash.

The older revision B1 is fine running any version of these firmwares.

2) What I usually do when using the Firmware Recovery tool:

a) Unplug everything from the router except for power and that one LAN cable going to the computer used for recovery. That means unplug the WAN cable as well - I have seen a few users who had issues caused by that

b) Leave the router turned off.

c) Start the Firmware Recovery tool, select the FW to flash (don't forget to unzip it first), then click on Upload. It will start looking for the router.

d) Turn the router on with the Reset button pressed. Wait 5 seconds, then release it.

e) The recovery tool will then see the router appearing in recovery mode, and start the upload.

f) The RT-N66U can take up to 10 minutes to flash. Be patient! Often, the recovery tool itself will not wait long enough. So even if it says that it no longer sees the router, still wait at least another 5 minutes.

Ideally, watch your router - when it's done doing its recovery all the LEDs will flash for a second as the router reboots itself. Give it another 2 minutes, and you should then see the wireless LEDs turn back on (assuming you didn't disable wifi). When the wifi leds are back on, it means recovery is complete, and the router has finished its reboot.

The whole process can take 10-15 minutes - the RT-N66U has pretty slow flash when it comes to writing. No idea if the new flash used in revision B2 is faster (or even slower), so to be safe give it up to 20 minutes.

 

[zhangla]

I had the exactly same issue with my brand new N66U bought yesterday from Frys locally.

I waited 1 hour after the Firmware Restoration says:

Failed to connect to the wireless router. Check if the router's power LED is blinking, which denotes that the router is in rescue mode

Still nothing happened. BTW - I was just trying to flash it to the latest ASUS official firmware for this router on their official website. I followed exactly the steps that everyone else doing. I had no issue flash my other routers, such as Netgear WRN3500L, etc.

Sometimes, the power LED will stay off after the Firmware Restoration posted the above message. Other times, power LED will stay solid on.

Mine is a B1 version printed on the bottom of the router. I suspect the newer batch of this router has some quality control issue.

Now I am on my way to Frys for a refund. ASUS seems to have quality issues.

 

[zhangla]

The other interesting thing about this router is, after the flash and waiting up to 1 hour, I unplug it and plug power back in, the router will go into rescue mode autmatically (without me pressing anything).

Has anyone had this problem? This router is full of issues... Flash firmware used to be a breeze for me, but not with this router.

 

[RMerlin]

Make sure you unzip the FW before flashing it.

Also, revision B1 is the "old" revision that has been sold for over 18 months. B2 is the newer one, which uses a new type of flash.

 

[havepatience]

Hello,

I've an RT-N66U (HW-ver: B1) from a friend of mine sitting here, which is showing the same symptoms like other have described in this thread.

The good thing: I'm connected to it via serial interface - using a USB TTL UART converter.

I've started a TFTP flash using Ubuntu 12.04. What I can see is, that the upload of the firmware of the device is never a problem. The problem is writing to the flash.

While the upload had been done within a couple seconds it took 40 minutes to switch from

Programming...

to

copysize=24231936, amtcopy=24231936
done. 24231936 bytes written

So does not look to bad, but is not back to the "CFE>" prompt yet.

Am I correct that the operation is still going on unless I get the "CFE>" prompt?

I'm waiting for over 90 minutes (since the whole process started) now.

BTW, for the moment power and lan leds (the one where the computer is connected to) are steady blue.

I will keep it sitting over night if necessary.

Thanks!

EDIT:
OK... the box is fixed. I'm back on ASUS stock firmware. I've had not the patience to let it sitting over night. I did not get back to the "CFE>" prompt on serial console. I just did power of the router, unplugged the power cord, pused the power button with no power cord connected to the unit reconnected the power cord and powered the router back on. And it did boot.

If somebody is interested in detailed instructions, let me know and I will post it here - even if I did nothing special that would not be described on the web already.

So my short advice, for people being caught in the recovery mode loop:

- Upload the stock firmware via TFTP
- Have patience, let the device sit after upload for 60 minutes

I don't now if the method of using ASUS recovery tool + patience would do the same. I could imagine that the recovery tool - cause it is comming up with the error message after a while - does may interrupt the flash process in this case.

As far as I remember after using the recovery tool to upload the firmware, the leds went of after a while and nothing else happened - but I could be wrong.

 

[RMerlin]

40 mins seem oddly long. When I had to use recovery on the RT-N66U, it never took more than 15-20 mins to reflash.

 

[havepatience]

40 mins seem oddly long. When I had to use recovery on the RT-N66U, it never took more than 15-20 mins to reflash.

I will clarify a couple things:

• My situation had not been exactly like the one of trauco.
• My situation had more been like zhanglas, so that the router was automatically booting to recovery mode, without forcing it to do so.
• Nothing did help out - realy nothing - to get out of the recovery mode. 30/30/30 reste would not behave like normal. After plugging the power back to the router, the recovery mode was entered before the last 30 seconds could run out.
• No web access to the web config. No access via SSH or Telnet.
• But I could ping the router in recovery mode and I could upload firmware using the ASUS Recovery tool or uploading via TFTP (I had no USB TTL converter at this point).
• Uploads have been always running without a problem, but I could still not get out of Recovery mode, even after leaving the device alone for 30 minutes. The Recovery tool did always end with the message: "Failed to connect to wireless router. Check if the router's power LED is blinking, which denotes that the router is in rescue mode."
• Before I started messing with the router, a friend of mine was trying for a couple weeks to flash it with third party firmware. So when he went from ASUS stock firmware to the first third party firmware - which he thinks was a Tomato build - he could never bring it back to a web GUI.
• So he forced the router into recovery mode, and from that point on, the router was never leaving the recovery mode again.
• He tried loading a various other third party builds to the router using the recovery tool but was always getting the error message from above.
• He was trying to upload via TFTP, but no luck with that, too.
• After making the same experience, I decided to get a USB TTL Serial CP2102 converter to investigate what's going on

Results of my - amateur - investigation:

• Hardware: RT-N66U - HW-Version: B1 - Board revision 3.20
• bl_version: 1.0.1.3 (so must be on of the devices, coming with 64k CFE preinstalled, cuase my friend did not update the CFE).
• Router did enter the recovery mode caused by a "Bad checksum error", which I guess does tell, that there is garbage on the router-os(?) partition. So former flash operations must have been never successful.
• So started a TFTP flash - intialized from serial console using

  flash -noheader : flash1.trx

  to check what error message would come up.
• But no error message came up. Instead after 40 minutes I've got the confrimation that kernel and filesystem had been written.
• But no automatic reeboot had been initialized after writing procedure.

My guess:

• Friend of mine has might been using a 32k Tomato build to flash this 64k capable router, which did cause the inital problem. Not sure about that yet.
• Every further flash operation was not successfull, cause the router had never enough time to write to the flash. --> proven true (see EDIT)
• ASUS recovery tool does may intialize a reboot to early, what will may cause the error message. --> proven false (see EDIT)
• Cause people are ending up in flashing over and over again, the filesystem on the flash gets messed up that much, that the flash procedure will take even longer than normal.
• As a result you will have a bad checksum os partition, that does force the router to enter recovery mode. --> proven true (see EDIT)

Situation after rescue operation:

• I had been able to flash from stock ASUS firmwar to your (Merlin) latest stable build, without a problem and within the 3 minutes that had been indicated during the operation. (Thanks, for your brilliant work BTW)

I might have been posting inside the wrong thread, but I just wanted to share the information, that this device seems to need a whole amount of time for the flash once it gots screwed up and I've the feeling, that the ASUS Recovery tool might not be helpful in such a situation, cause it might interfere the on-going write procedure to the flash.

But I've not done that much investigation. So I could be wrong as far as it belongs the ASUS recovery tool.

I hope, I don't spam this thread with all this information.

Thanks!

EDIT:

I did a few more (4) flashes using the recovery mode to find out a bit more:

• ASUS Recovery utility does not interfere the recovery process. But it does come up with the error after counting down round about 15 minutes, even if the router is still flashing kernel and filesystem. So you must ignore that dumb error message.
• The tool does not communicate with the router at the point where it's coming up with the message. Seems to be that it just lets count down 15 minutes and does check after they run out, if 192.168.1.1 is reachable again. Which it is not, cause it is still programming at this point.
• Apart from that confusing message, the Recovery tool does operate correctly.
• The difference between using the Recovery tool and TFTP is, that the Recovery tool does intialize a reboot at the end of the procedure, a TFTP upload does not.
• If the flash from within the Recovery mode does fail, there is a high risk, that the router does enter the recovery mode with every new start, as long as no new flash is successful.
• Before starting any firmware flashs I would enabel the wireless radio - if you should have disabled it before. The wireless leds are the only indicators to let you know, that the router has rebooted after a successful flash, cause the leds are off in recovery mode.
• First I thought, the power led would may indicate that the kernel and filesystem is written at the moment, cause on two tries they had been off during that stage. But on an other two tries, it was steady blue while programming. So don't get confused with it.
• All flashes I did from within the recovery mode took around 40 minutes. It is not a must that it will take the same time for every RT-N66U. But if you do a flash from recovery mode, then use the ASUS recovery tool and give this device enough time and ignore the error message, if you get one.

EDIT2:

Some more findings about the Recovery/Rescue mode:

• If you don't have Windows machine so you can not use the ASUS Recovery tool and you're uploading the firmware inside Recovery mode using a TFTP programm or you're doing it through the 192.168.1.1 CFE rescue page, don't ignore error messages during the upload, telling you something about timeout during the upload procedure. You can turn the router off in such a situation and turn it back on - holding down the reset button - to bring it back into Recovery mode and try it again until the upload is successful. I'm just talking about the upload process of the firmware file from the computer to the router at this point. I'm not talking about the programming procedure, which does follow the upload and that does not give any message back to you and during that you simply have to wait long enough.
• An error message belonging to the upload process will result in a corrupted flash. The ASUS seems not to check a checkusm or the size of the upload file before or after uploading. It will start to program to flash memory, even if it just has received half of the firmware file.

A general may be helpful note - before starting any flash procedures:

There are a couple of instuctions on the web, telling you that there would be no way to find out, what CFE version you have until you have switched to an other firmware - like Merlin build etc.. But you can go to the hidden Admin page on stock firmware - tested with ASUS stock FW_RT_N66U_3004374257 - which you can find under 192.168.1.1/Main_AdmStatus_Content.asp. There you can execute:

strings /dev/mtd0ro | grep bl_version

It will show you the CFE version. You can run any other command (e.g. "uname -a" oder "nvram show") there, to get out information from the RT-N66U.

 

[fe1509]

Hey, i guess i've a situation similar to yours but i could not understand which result you got after doing all this. (my rt-n66u only has the power led light on and only responds to ping when in recovery mode).

I've tried to upload asus stock FW and Merlin's FW using asus recovery tool, but, it doesn't find the router.
Then i've tried to do it using TFTP and i couldn't get it either, but i did managed to upload a dd-wrt FW that is supposed to work.
So after the upload my router stays with the power led light steady blue and i won't get any response from ping.

Should i let it there flashing? or do a power cycle and than let it still ?

I hope that i can do something this way, i've read some serial/jtag solution but i don't have the necessary hardware or knowledge to do this.

 

[stray77]

Good Luck, be patient.

qwell and I both had the same issue and both of us resolved it here.

http://forums.smallnetbuilder.com/showthread.php?p=77870#post77870

 

[phoenixblue]

Adding another thumbs up to the long wait verification

40 mins seem oddly long. When I had to use recovery on the RT-N66U, it never took more than 15-20 mins to reflash.

I would generally agree with this through experience upon nearly 100 custom routers being flashed with either DD-WRT or Tomato. However, I was having the exact same issue trying to get a RT-N66U back to stock from DD-WRT and the darn thing took closer to 55 minutes before the flash completed.

I originally wasn't waiting long enough, and could ping the router in recovery, so I do not know if WPS button trick helped that last time I attempted. But I did it regardless and walked away for 45 minutes to come back to it still being in flash mode. 10 minutes later the lights flashed and it rebooted.