Linksys WRT1200AC V2 semi-bricked

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Jowshuf
DD-WRT Novice


Joined: 05 Jan 2022
Posts: 3

PostPosted: Mon Jan 17, 2022 22:59    Post subject: Linksys WRT1200AC V2 semi-bricked Reply with quote
Hello everyone,

I have a Linksys WRT1200AC V2 and I can't login into it nor flash to reset it. The router lights up, boots up and I can get to the login prompt of it. I did try to switch the partitions and I believe DD WRT is flashed on both, and on both partitions the login information is lost, SSH is disabled I believe (receive connection refused on both) and I believe the reset button doesn't do anything either (Not 100% sure on this). I bought 2 different model USB to serial cables and tried to follow the below guides. I bought 2 because I thought maybe one was broken. I've tried Windows and Ubuntu with Putty and Screen and neither show anything on either cable. I don't see any output on either machine/cable/software. I also cut into one of the crappier cables because the connections to the pins were wobbly but still no output on Putty or Screen.

Guides used:
https://www.youtube.com/watch?v=PZYXKAkuJ5w&t

https://fabianlee.org/2016/07/20/ubuntu-serial-level-access-to-your-linksys-wrt1x00acs/

Cables:
https://www.amazon.com/gp/product/B00QT7LQ88/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B08BLKBK1K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Any help is appreciated. Thx for reading my blog.
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kernel-panic69
DD-WRT Guru


Joined: 08 May 2018
Posts: 12472
Location: Texas, USA

PostPosted: Tue Jan 18, 2022 0:38    Post subject: Reply with quote
I use a pitch adapter cable to connect to this style of serial connector on Linksys. If your serial client is set correctly, your cable TX lead goes to router RX pin and your cable RX lead goes to your router TX pin.

If ssh isn't answering, check telnet. Does the DD-WRT web interface come up when you use a browser? Is the router serving IP addresses at all? Default IP of router is 192.168.1.1.

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Jowshuf
DD-WRT Novice


Joined: 05 Jan 2022
Posts: 3

PostPosted: Tue Jan 18, 2022 2:08    Post subject: Reply with quote
Hello! The DD-WRT web interface doesn't come up, but when I go to 192.168.1.1 with my web browser, I just get a prompt for a username/password. When I cancel the prompt, it says...

"401 Unauthorized
Authorization required. please note that the default username is "root" in all newer releases"

It does assign IP addresses. I've tried the reset button while it was off, on, 30 seconds, a minute...
blkt
DD-WRT Guru


Joined: 20 Jan 2019
Posts: 3897

PostPosted: Tue Jan 18, 2022 2:24    Post subject: Reply with quote
Reset button is only 10 seconds after powered on and after full boot.

First time you log in it will ask to set username, password, password.

Be sure browsers have not saved password, autofill or autocomplete.
kernel-panic69
DD-WRT Guru


Joined: 08 May 2018
Posts: 12472
Location: Texas, USA

PostPosted: Tue Jan 18, 2022 2:25    Post subject: Reply with quote
And it is still prompting for a user/pass (that you don't know the password for, I presume). Could be on a build that the reset button was broken. Normal reset is around 10 seconds push of the button with the router powered up. If it's not resetting, you're going to have to flash via serial. I don't recall if there is a way to reset nvram via u-boot/serial, but if it's not in the stickies in this forum, check the OpenWRT wiki:

https://openwrt.org/toh/linksys/wrt_ac_series

_________________
Official Forum Rules, Guidelines & Helpful InformationFirmware FAQInstallation WikiWhere Do I Download Firmware‽
DON'T use Chromium-based browsersRTFM/STFW TL;DR is NOT an excuse. • Why Should I Care What Color the Bikeshed Is‽
Please DO NOT PM me with questions; Ask in the forum. ---------------------- Linux User #377467 counter.li.org / linuxcounter.net
Jowshuf
DD-WRT Novice


Joined: 05 Jan 2022
Posts: 3

PostPosted: Wed Jan 19, 2022 15:39    Post subject: Reply with quote
Thank you for the suggestions! I have tried holding the reset button and WPS button (together and each separately) for 10 seconds but unfortunately, that doesn't work either. I'm curious, is that a way to not show serial output? Could malware do that?

*Edit*
Also, I've read that you should test your USB to serial cable. Is there a guide for that...?
kernel-panic69
DD-WRT Guru


Joined: 08 May 2018
Posts: 12472
Location: Texas, USA

PostPosted: Wed Jan 19, 2022 16:04    Post subject: Reply with quote
Shorting TX/RX on serial cable should echo whatever you type to PuTTY, minicom, etc.
_________________
Official Forum Rules, Guidelines & Helpful InformationFirmware FAQInstallation WikiWhere Do I Download Firmware‽
DON'T use Chromium-based browsersRTFM/STFW TL;DR is NOT an excuse. • Why Should I Care What Color the Bikeshed Is‽
Please DO NOT PM me with questions; Ask in the forum. ---------------------- Linux User #377467 counter.li.org / linuxcounter.net
blkt
DD-WRT Guru


Joined: 20 Jan 2019
Posts: 3897

PostPosted: Wed Jan 19, 2022 17:10    Post subject: Reply with quote
May need to connect ground wire after power on. Or, maybe just loose connection.

https://www.amazon.com/2-54mm-2-0mm-pitch-Header-Adapter/dp/B00HFZK652

Be sure your driver is correctly installed, also properly selected COM port settings.
SurprisedItWorks
DD-WRT Guru


Joined: 04 Aug 2018
Posts: 1328
Location: Appalachian mountains, USA

PostPosted: Thu Jan 20, 2022 19:28    Post subject: Reply with quote
As someone pointed out above, the password prompt you are seeing is NOT asking you to remember your password. It is asking you to create a new password. Make up something and confirm it. Use "root" (no quotes) as the username.
_________________
Six Linksys WRT1900ACSv2 routers on 48141: VLANs, VAPs, NAS, client mode, OpenVPN client (AirVPN), DDNS, wireguard servers and clients (AzireVPN), three DNSCrypt DNS providers (incl Quad9) via VPN clients.
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