RT-AC88u kaput after most recent ASUS update

[newb]

I was on MERLIN's firmware 15. For whatever reason, I flashed to the newest ASUS original.
Then I saw Merlin's 16 and wanted to switch - and this was the end. The message came up that the Merlin's firmware I tried to flash is not authirized. Well I though to flash to a lower ASUS original - it went in only after the reset. So I wanted to Restore cfg that I have saved before. It went in. But when I entered the usual or any login I could imagine it reported WRONG PASSWORD.
So I tried to do RESTORATION. I pressed and held the red reset button and powercycled, and held the reset until it went into slow blink. I started the Restoration ASUS utility - which after 30 second reported that the router is not in restore mode. I played this for 24 hours making some variations, assigning IP manually, spitting thru my left and then right arm three times. No go.
I can get it reset and working - but cannot update to any firmware without getting wrong password; and cannot restore prior cfg either. So it works but it does not.
What do I do?

 

[L&LD]

Try the WPS button reset. Power of the router. Wait a minute or two. Hold down the WPS button and power on the router. Keep holding the WPS button until the router either reboots or shuts off.

Power up the router and you'll need to use the Rescue mode to flash the RMerlin firmware you want.

https://www.asus.com/support/faq/1000814/

 

[newb]

Try the WPS button reset. Power of the router. Wait a minute or two. Hold down the WPS button and power on the router. Keep holding the WPS button until the router either reboots or shuts off.

Power up the router and you'll need to use the Rescue mode to flash the RMerlin firmware you want.

https://www.asus.com/support/faq/1000814/

did that - does not work on rt-ac88u at all. Simply does nothing.

 

[L&LD]

Keep doing it until it works.

Unplug the router from the power and all cables and USB connections/drives. Wait at least 2 minutes before attempting once more.

 

[RMerlin]

But when I entered the usual or any login I could imagine it reported WRONG PASSWORD.

This is expected. The latest Asus firmware for that model now encrypts the user password. If you switch back to my firmware without erasing your settings afterward, you will no longer be able to log in, as my firmware will expect you to enter the encrypted version of the password.

A factory default reset is now mandatory when going from the latest RT-AC88U stock firmware to either my firmware or any older Asus firmware.

 

[whitey019]

RMerlin: Wouldn't the default password still be encrypted after a factory default reset?