very stubborn corrupted NVRAM

Discussion in 'Tomato Firmware' started by sjs, Sep 19, 2009.

  1. sjs

    sjs Network Guru Member


    i am using a Asus WL-520gu, and was successfully using SGTPepperKSU's VPN mod, but then i pasted in a very long OpenVPN key.

    immediately i noticed some other random GUI settings were now mistakenly empty. oh boy, i've seen this before, i probably overflowed the NVRAM buffer, so i checked

    $ free

    and sure enough it said I had negative bytes free. it then locked up.

    i thought it was bricked, and i can not see it in the Asus Firmware tool.

    luckily i was and am still able to tftp to its OLD IP address (, and i have, a dozen times already, but i still cant get to the GUI.

    so i can easily get the router into Recovery Mode, at which point I can see the ping is TTL=100

    and then i can successfully tftp any firmware i choose. but thats as far as i get.

    i've tried tftping the special "clear nvram" firmware, from the steps here:


    and that too, is successfully tftp'd. i wait 5min. then tftp a known firmare. yet i can never get the IP to reset back to defaults, i can never get to a GUI.

    it is effectively bricked, despite being able to TFTP, due to the bad NVRAM i think.

    the only other thing i could try would be the short out pin 10 trick.

    but i thought that was only for people who could not get into recovery mode, which isnt me. i just need to clear bad nvram. hate to open it up if thats not needed. do i have any other options? thank you for any suggestions.
  2. Toastman

    Toastman Super Moderator Staff Member Member

    I don't have any other advice but please wait for a while before you decide to short any pins. More routers have been destroyed by doing this than I've had hot dinners. It sounds to me like you may have to use jtag...
  3. sjs

    sjs Network Guru Member

    thanks. here's an update:

    the Asus Device Disovery Utility still does not see the 520gu when in recovery mode-- however i just realized that the other tool, the Asus Firmware Restoration utility is able to successfully flash the unit.

    nothing changes though. its just like me flashing it over and over from the cmd line.

    i can put whatever firmware i want on there.

    its still dead.


    how can i clear the nvram?
  4. mstombs

    mstombs Network Guru Member

  5. rhester72

    rhester72 Network Guru Member

    Might have luck flashing OpenWRT and issuing a "mtd erase nvram" - but this *COULD BRICK THE ROUTER*, so use caution!

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