RT-AC88u: Failed to upload the firmware file transfer cancelled

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iceblue1980

Occasional Visitor
Hi guys,

I just bought couple of broken RT-AC88u units from eBay and they seem to have same issue: when trying to update the firmware (tried stock and Merlin), I get this error at 98% completion:

"Failed to upload the firmware. File Transfer Cancelled"

I am an advanced repair enthusiast so needless to say I followed the proper steps of erasing the NVRAM, successfully rebooting into Rescue mode, adding fixed IP to the PC and tried all 8 LAN ports with nothing else connected to the router. The only firmware I am able to import is DD-WRT (because it is under 30Mb in size?) The CFE website works but the upload through CFE doesn't work at all. The router just returns to Rescue Mode.

I have connected the router to the bench power supply (19V / 3A setting) but noticed that the router pulls 0.49 amps at best..

I have ordered the TTL cable and was thinking if that would perhaps solve the issue.. But i'm doubtful.

When I boot the router normally only Power Led is on and 2.4GHz. The DD-WRT open WiFi is detected but I can't connect to it to access the web ui. It seems that the 2.4GHz connection is breaking every 3 seconds. All LAN ports are completely dead.

Here is my question - am I looking at a hardware error? I'm no stranger to hardware mods (soldering, rework, etc) so would be good to know where to begin if this is indeed a hardware issue.

Cheers all
 

thecheapseats

Regular Contributor
I'm likely wrong - but I vaguely remember reading here that you needed an older, smaller version of an asus firmware image to allow it to load into the dd-wrt constrained memory space via tftp or whatever method the rescue firmware uses, to play 'fool-the-machine' and get out of dd-wrt jail... hope you get it working... and a ttl serial cable is always nice to have laying around, too - so there's that...

(edited for clarity)...
 
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iceblue1980

Occasional Visitor
I'm likely wrong - but I vaguely remember reading here that you needed an older, smaller version of an asus firmware image to allow it to load into the dd-wrt constrained memory space via tftp or whatever method the rescue firmware uses, to play 'fool-the-machine' and get out of dd-wrt jail... hope you get it working... and a ttl serial cable is always nice to have laying around, too - so there's that...

(edited for clarity)...

That's the thing. I've been trying to find it, even reached out to Merlin. Looked at Asus website. Searched Google... Wonder what search parameter I could use to find this old firmware?
 

thecheapseats

Regular Contributor
That's the thing. I've been trying to find it, even reached out to Merlin. Looked at Asus website. Searched Google... Wonder what search parameter I could use to find this old firmware?
somebody put a link up here VERY recently for an off-asus-site collection old asus firmware images... hope that link is still here... if you get lucky and find one that's sized right, ask around here for someone to do a checksum on that version rev in their possession to confirm what you d'loaded is still a 'virgin' before you upload it - (sorry I probably didn't need to tell you that last part)...
 
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iceblue1980

Occasional Visitor
somebody put a link up here VERY recently for an off-asus-site collection old asus firmware images... hope that link is still here... if you get lucky and find one that's sized right, ask around here for someone to do a checksum on that version rev in their possession to confirm what you d'loaded is still a 'virgin' before you upload it - (sorry I probably didn't need to tell you that last part)...

The only link I found was for AC68u model. Do you remember any thread titles?
 

ColinTaylor

Part of the Furniture
The only link I found was for AC68u model. Do you remember any thread titles?
I think the post he was remembering was this one, but that's only for the RT-AC86U.

I checked all the official and Merlin firmwares for the 88U going back to 2017 and they're all over 32MB, so if that's your problem then you're likely out of luck. Surprisingly the smallest firmware (at 33MB) is Merlin's current release, 384.19_0.
 

iceblue1980

Occasional Visitor
I think the post he was remembering was this one, but that's only for the RT-AC86U.

I checked all the official and Merlin firmwares for the 88U going back to 2017 and they're all over 32MB, so if that's your problem then you're likely out of luck. Surprisingly the smallest firmware (at 33MB) is Merlin's current release, 384.19_0.

Yeah this is exactly what he said. I was hoping to find old stock firmware that was under 30mb. I wonder how Rescue Mode deals with the partition limit in normal cases, since users seem to be able to flash firmware in general, i.e when the router isn't bricked?
 

ColinTaylor

Part of the Furniture
Yeah this is exactly what he said. I was hoping to find old stock firmware that was under 30mb.
I don't think there has ever been a stock firmware for the 88U that was less than 32MB.

I wonder how Rescue Mode deals with the partition limit in normal cases, since users seem to be able to flash firmware in general, i.e when the router isn't bricked?
The issue with some other models (which may not apply the the 88U) was that they normally have a firmware partition size of 64MB. Installing DD-WRT changed that to 32MB which meant that you can't simply re-upload the stock firmware.
 

iceblue1980

Occasional Visitor
I don't think there has ever been a stock firmware for the 88U that was less than 32MB.


The issue with some other models (which may not apply the the 88U) was that they normally have a firmware partition size of 64MB. Installing DD-WRT changed that to 32MB which meant that you can't simply re-upload the stock firmware.
Oh that is some excellent insight! Many thanks. So I need then to figure out how to bypass that fake limitation
 

thecheapseats

Regular Contributor
Yeah this is exactly what he said. I was hoping to find old stock firmware that was under 30mb. I wonder how Rescue Mode deals with the partition limit in normal cases, since users seem to be able to flash firmware in general, i.e when the router isn't bricked?
well rats - sorry I didn't realize it was for ac86 - I skimmed the comment... I did look at the oldest ac88 firmware I had from several years ago - and yes around the 31-32meg size... there's gotta' be a way to torture the board into submission - there always is... good luck...
 

iceblue1980

Occasional Visitor
I actually managed to upload the latest Merlin firmware through TFTP and it was a success. Did NVRAM wipe afterwards, restarted the router and it keeps rebooting itself. I flashed stock firmware (same version as was on the router according to the label on the bottom, i.e 3.0.0.4.380) to nflash1 but that didn't solve the bootloop and then I flashed Merlin's latest firmware to nflash0 but that didn't help either.

I'm attaching the boot log in case someone can spot an issue and share it with me. Cheers guys
 

Attachments

  • putty_log_asus_rt-ac88u_bootloop.txt
    27.9 KB · Views: 31
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thecheapseats

Regular Contributor
did that ttl serial cable show up yet?... how are you getting in? lan port?...
 

thecheapseats

Regular Contributor
wait - or was it a jtag cable you (somehow) spec'd and ordered?...
 

iceblue1980

Occasional Visitor
did that ttl serial cable show up yet?... how are you getting in? lan port?...

I got TTL cable from Amazon.

All drivers are installed and COM ports are configured. I have connected to J3 socket on the motherboard. Since I managed to communicate with the router, I am fairly confident the connection is stable. I connected the LAN cable to port2 on the router since ports 1, 5-8 are part of the secondary switch rather than primary network.
 
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thecheapseats

Regular Contributor
something isn't letting loose - did you wps reset with the both lan and serial disconnected? - I ask because in a very old ancient part of my brain I recall some odd-ball firewall or router (can't remember which - more than 20 years old by now) - it wouldn't allow a factory reset without all the cables disconnected - it was a fail safe 'thing' as I recall for remote co-location if 'out-of band' comm failed or ?something? like that... probably not applicable here... I'll stop guessing now...
 

iceblue1980

Occasional Visitor
something isn't letting loose - did you wps reset with the both lan and serial disconnected? - I ask because in a very old ancient part of my brain I recall some odd-ball firewall or router (can't remember which - more than 20 years old by now) - it wouldn't allow a factory reset without all the cables disconnected - it was a fail safe 'thing' as I recall for remote co-location if 'out-of band' comm failed or ?something? like that... probably not applicable here... I'll stop guessing now...

Tried that, same result. Was there anything in the log file that you noticed?
 

thecheapseats

Regular Contributor
cfe from serial - not syslogd as you can't get that far... just don't know...
 

iceblue1980

Occasional Visitor
cfe from serial - not syslogd as you can't get that far... just don't know...

I have soldered the pins to access JTAG mode and my adapter is supposed to arrive later today. I'll share the log.

I wonder if I can find a bootlog of a healthy RT-AC88u.. That would certainly help.
 

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