Unbricking LInksys WRT1900AC v1

Installing and Using OpenWrt
1

Hi all,

I am trying to unbrick my router with a USB-TTL cable to flash the factory firmware. After hooking everything up, I flip on the router, when PuTTY gets to the part where the router is about to boot up, I have 3 seconds to hit any key to halt it in order to load the OEM firmware. However, when I hit a key on my laptop (that's what I'm using), it does nothing - the router just continues to boot up in PuTTY. Can anyone tell me what am I going wrong that hitting any key on my laptop does nothing to stop it from booting?

Thank you.

2

You may have already done this, but just in case, have you tried booting to the other partition? If you have and it didn't work, I'd suggest following the instructions in this video, it gives a good walk through of the steps needed.

3

Hi Mike,

Thank you for your response. Yes, I have switched partitions. In fact, I'm doing this because only partition 2 of the router is bricked. I just don't understand why it won't stop it from booting when I hit the space bar (or any key on the keyboard for that matter). Quite frustrating.

4

Sure about the connectivity, if you can switch partitions you should be able to flash over the bad one if you don't care about content.

5

Hi anomeome,

Thank you for your comment. Yes, I'd like to flash the OEM firmware to only the bricked partition - if I could stop PuTTY from booting the router by "hitting any key" - therein lies the problem - no matter what key I hit on the keyboard, it wouldn't stop it from booting the router!

6

Turn off Flow Control on the putty configuration. That will suppress keystrokes on most embedded serial connections.

7

Thank you for the tip t4thfavor. I will give that a try.

8

Sadly, turning off Flow Control does not stop the router from booting.

9

It should print characters at least. If it doesn’t, then you have some incorrect setting, or your ttl connection is not connected to the tx terminal properly.

96008n1 no flow control is what works for me 99% of the time, the rest is when I have a bad usb to serial adapter or a physically broken wire somewhere.

10

mamba is 115200. But, if you can successfully boot to the other partition, than why can you not just flash OEM from there (by whatever means, GUI, ssh).

11

It does print characters. However, when it gets to the part where it gives me 3 seconds to "hit any key" to pause the router from booting - when I hit a key on my keyboard, it doesn't stop it from booting the router.

12

I have OpenWRT on the good partition and I'd like to keep it. It's the partition I bricked that I'd like to revive.

13

Right, so go to the OpenWrt partition and flash OEM.

14

So you're saying - by being on the partition with the OpenWRT, head over to "Administration", flash OEM and it will flash the OEM onto the bricked partition?

15

To support failsafe, sysupgrade is a round-robin, it flashes to the other partition, not the current partition. Not sure about OEM from the GUI, may have to ssh in to upgrade.

16

Thank you all for your tips, suggestions and comments. I really appreciate it. Will let you know how it turned out.

17

Short RX and TX on the USB-TTL and see if you get an echo

18

Thank you for the tip Nico1320. I will give it a try.

19

Do this: How to flash firmware to Linksys WRT1900AC.

I did it in 2016, and it worked for me. Since then, I've left the USB to TTL cable connected to the router. (Let me know if you need an image of this)

Please note all the parameters set.

20

this is really easy.
download the official firmware for your router.
flash the official firmware from openwrt luci, just make sure to not keep setting and force installation.
or you can put the immage in /tmp and flash it via ssh
sysupgrade -n -F name of your firmware