After a successful installation of 14.07 r42625 on a new wdr3600, I was playing around, installing additional packages and mounting a usb flash drive until, one morning I turned it on and it failed to appear on my network. None of the previously configured or default network connections were available.

   I reflashed several times using the power on w/reset button pressed tftp method. These attempts seemed to work, the file seemed to transfer correctly and the router reset but the system led never lit up and no network connections were configured.

   I connected my max232 rig to the serial header and was able to obtain a console to the bootloader where I observed the kernel load and start and then errors like:
[    2.440000] VFS: Mounted root (squashfs filesystem) readonly on device 31:2.
[    2.440000] Freeing unused kernel memory: 272K (8034c000 - 80390000)         
[    2.750000] SQUASHFS error: xz_dec_run error, data probably corrupt         
[    2.760000] SQUASHFS error: squashfs_read_data failed to read block 0x6e     
[    2.770000] SQUASHFS error: Unable to read data cache entry [6e]             
[    2.770000] SQUASHFS error: Unable to read page, block 6e, size 259f4       
...
[    2.860000] SQUASHFS error: xz_dec_run error, data probably corrupt         
[    2.870000] SQUASHFS error: squashfs_read_data failed to read block 0x14157e
[    2.870000] SQUASHFS error: Unable to read fragment cache entry [14157e]     
[    2.880000] SQUASHFS error: Unable to read page, block 14157e, size 10ad8   
...
finally ending in Kernel panic.

   I tried doing all the steps of reflashing manually from the console (tftp, erase, cp.b) and wound up with the same result. I even tried to reflash the tp-link firmware.

    Is there anything else to try or am I correct in assuming part of the flash chip is toast and the only solution is to replace the chip?

   The part seems to be Winbond W25Q64FVSSIG (printing on surface:25Q64FVSIG). Any known problems with these? Any recommendations for a better part to use?

thanks in advance for any advice.

Try:

1. Power off
2. Power On, press the reset button  on the back very, very fast over and over until you see the 'asterisk' light blinking rapidly. When the asterisk light is rapidly blinking the router is in failsafe mode.
3. Go to a wired PC that is connected to router.
4. Manually set IP/Mask/Gateway to 192.168.1.2/255.255.255.0/192.168.1.1
5. Telnet in, 192.168.1.1
6. mtd -r erase rootfs_data (this resets openwrt back to factory defaults, erasing all settings). Router will reboot.

7. Reflash openwrt or reinstall packages.

(Last edited by kgoerbig on 12 May 2015, 02:36)

Serial into the bootloader erase firmware area of flash chip then use md.b to examine to see if it is all FF.  If that works, proceed to write all zeros and check that they all wrote.  If not, there is hardware failure (stuck bits) and flash chip needs replacing.  Which seems to be the case here.  Nothing ever (intentionally) writes to the squashfs.

You can build and boot an initrd openwrt and use that to extract your bootloader and more importantly, ART partition, before removing the bad chip.  Use a chip programmer to write these into new chip.

(Last edited by mk24 on 12 May 2015, 02:40)

Thanks for your post.  I goofed when installing Chaos.  I ended up installing it from firmware update while the TP-Link firmware was still installed.  Didn't noticed I was supposed to do the TFTP method, until after I started the update process.  I use the steps you listed, and was able to access the router with Chaos already installed, but kind of glitchy.  Did a factory reset, then reinstalled the Chaos firmware again, and now everything is like butter.

Was worried I bricked an unused WDR3600.

@WeirdG You should be using LEDE not CC!
CC is old now. https://lede-project.org/