OpenWrt/LEDE Project

  • Status Unconfirmed
  • Percent Complete
  • Task Type Bug Report
  • Category Base system
  • Assigned To No-one
  • Operating System All
  • Severity Critical
  • Priority Very Low
  • Reported Version openwrt-21.02
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by Scrotos - 11.07.2021

FS#3927 - OpenWrt 21.02.0-rc3 bricks Netgear WNDR3700 v4

I saw the announcement on the website about the next stable release so like an idiot I went to upgrade the firmware. Router never came back, left it on overnight to see if it would eventually come up. I was upgrading from 19.07.7.

Breaking open the case I see a UART header and some pads for a JTAG but I’m not the guy to debug what broke. I just wanted to give someone else a heads up so they don’t lose their router, too.

The debricking guide is some random notes for people who jump into the hardware, not really organized in any understandable way.

I like the line “The usual recovery methods have failed, forceing the user to to go to JTAG.” Like, where are the usual recovery methods listed? Not in the debricking guide, they aren’t.

Sorry, it’s just frustrating for a somewhat literate user like me (coming from LEDE, 20-ish years in IT/networking/sysadmin crap) that the debricking guide is useless for me. No “here’s the steps the OS takes to initialize” and “here’s where a safemode kicks in where you can set some TFTP or here’s where you pop into the serial connection via PuTTY” or like a general list of steps in order that you can attempt before working up to “ok solder a JTAG connector, here’s a DIGIKey part number to get you started.”

Tried Failsafe, Factory Reset, and Recovery all with no dice.

Walter Sonius commented on 12.07.2021 12:13

Documentation can always be improved for instance on level of detail, scope or even the skill of the user. Its almost a dynamic thing serving different needs for different users, but in its current form it is indeed generic for different kind of hardware and problems. It describes roughly 3 steps of pointing in which direction the problem may exist. Not talking about a specific problem nor about any solution in sight yet!

It seems you have followed the "1st" failsafe procedures which are indeed not specifically written for your hardware/problem (scattered around wiki/forum/etc/pages). It will help us, if you specifically described what behavior of which leds and timings on your router are responding to draw better conclusions of what may be wrong. This stage is however incredibly vague since different routers use different leds/timings/buttons whatever so I would skip this stage if you haven't took the time earlier to know/understand/verify the leds/buttons responses from a "correctly" working router. Its kind of a blind process, time consuming trial and error procedure... try these procedures the next time before trusting the hardware (to late now). Readon.

However the "2nd" step in this debrick/guide process you started, but never mentioned finishing quoting: "Breaking open the case I see a UART header and some pads for a JTAG but I’m not the guy to debug what broke" is very important! Also it may not only bring you to a specific problem but also very close to a possible solution.

In the worst case if you only have header holes on the board, soldering 3 pins for uart and cabling it to a "Raspberry Pi" may bring you unique and valuable insight in text/code form what the problem is exactly. It might even give you the interaction to solve it. Having access to a soldering iron and a Raspberry Pi can be of great value on the 20-ish years IT-skills you already had. Not doing this step may lead to the premature conclusion that the debricking guide is useless! The next step using jtag an recovering bootloaders may not even be necessary!

Not sure if you want/need specific guidance on your debricking problem since one obvious reason for your BUG report is warning others which is a good thing. But I'm quite sure you are quite lucky with this v4 being (atheros) and not broadcom based revision of your routers and you have very high chances of de-bricking it your-self as a OpenWrt developer (not user). Albeit via (tftp) recovery software in Windows from Netgear itself, might work on different models...

Just post more "usefull" info in this bug report, because it will probably be some kind of bootloader kernel/partition size thing which is very likely to get fixed. See this as an example report:

bob commented on 19.07.2021 18:05

I have the same router and, like you, found that sysupgrade left the router unable to boot, though the bootloader itself was OK.

I then successfully flashed the factory image via tftp; see my comment in #3931 for details.


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