GT-AC5300 bricked router - No keyboard input over serial

[vaboro]

I was installing minicom to tinker with the serial port of my AC86U and incidentally saw this:

Text Input Not Working
======================
Most development boards require Serial port setup -> Hardware Flow
Control to be set to "No" to input text.

Not sure what this means. I have FT232RL MCU based interface and text input works fine.

 

[RMerlin]

I was installing minicom to tinker with the serial port of my AC86U and incidentally saw this:



Not sure what this means. I have FT232RL MCU based interface and text input works fine.

As it says, when you configure the serial port in your terminal, make sure flow control is disabled.

 

[vaboro]

As it says, when you configure the serial port in your terminal, make sure flow control is disabled.

It might well then be serial port misconfiguration in the terminal that inhibits keyboard input in issue #3

3. CFE/WPS mode??

As far as issue #2

2. Rescue boot:

is concerned the tftp server with the firmware update might be down and that is why the router reports the error messages.
As about issue #1

1. Boot loop:

it looks like ASUS recovery software doesn't finish properly. As normal-boot.txt shows the router initialization crashes in the middle of the road. I wouldn't call it a boot loop. It looks more like a crash during the booting process. Seems like the result of unfinished firmware flashing.

Might consider flashing the firmware not with ASUS recovery tool but via custom tftp server.

 

[vaboro]

I recently had a boot loop issue with AC86U. I recovered by the following steps:
1) reset nvram by holding wps and powering the device on
2) as soon as CFE prompt appears power the device off, disconnect power cord and switch the device on to discharge capacitors
3) reconnect the power cord, turn the device on and enjoy normal boot
Seems like the problem was in some nvram settings surviving nvram reset if power is not completely disconnected and capacitors depleted.