No video when trying to unlock Lenovo T420

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  • aaroncm
    New Member
    • Jun 2022
    • 2
    • Australia

    #1

    No video when trying to unlock Lenovo T420

    Hi guys,

    Today I pulled 5 Lenovo T420 laptops out of a bin at the rubbish tip, and they're old school laptops and they're all locked with a supervisor password.

    In the past I've unlocked similar Lenovo laptops, often I used the trick of shorting a few pins together on the chip on boot to get into the GUI and overwrite the config but it doesn't look like that is working with these laptops. I guess Lenovo fixed that trick? I have unlocked some other HP laptops by reading the chip, running a patch and re-writing back.

    But I can't work out these T420 laptops.

    I followed this guide: https://www.badcaps.net/forum/showthread.php?t=87588

    And everything worked fine, I even got to step 6. But after I flashed back the original BIOS binary I had no video output at all. I mucked around for ages but I eventually got another one of the 5 laptops from the tip, verified it booted and was locked, and started again... except this time I never made it to step 6. After flashing the chip with the modified bios (after reading and patching) I got no video once again.

    I'm using a USB SkyPro chip reader. I'm also using a Windows XP SP2 VM passing thru the USB. (Only using the VM to read/write the chip)

    It detects the chip as a winbond W25Q64JV-IQ (8MB)

    The chip itself on the laptop is a winbond 25Q64FVSIQ. I can't find this exact chip in the software.

    But I read the chip multiple times with the same checksum. I followed the guide and used lenovo_autopatcher_0.2. It generated a patched bios binary.

    This was the output:

    Code:
    C:\Users\aaron\Documents\xp\lenovo_autopatcher_0.2\lenovo_autopatcher> .\autopatch.cmd BIOS4.bin
     
    Using UEFIReplace to inject 2 DXE drivers...
    [1/2] BootOption (GUID e0746c42-d3f9-4f8b-b211-1410957b9ff5)
    [2/2] LenovoTranslateService (GUID 826bcf56-bac4-43f4-8ea1-8cdf0a121abd)
     
    Looking for volumes to patch...
    [1/1] NVRAM_EfiSystemNvDataFvGuid (checksum 2609h):
       Not found... Skipping.
     
    Done.
     
    PATCH FILE: BIOS4_PATCHED.bin
    I then flash the binary and... no video. The chip is correctly soldered on and it's definitely working. It powers up, the power led flashes 4 times and then I get a steady green. Fan spins, LCD would be about to come on but... nothing...

    What I find weird is that everything was working fine, I didn't have any video issues until after step 6 on the first laptop, and then on the second laptop I got the no video issue as soon as I tried writing the patched bin to the chip...

    I also found this thread and tried the BIN found here with the same result: https://www.badcaps.net/forum/showthread.php?t=81573

    I also found people saying that it's a good idea to clean the ME. I found this guide: https://www.badcaps.net/forum/showthread.php?t=88533

    But it made little sense to me. I tried to follow the steps until I got to step 3, open the BIOS. I wasn't sure if I'm supposed to open the "ME Region.bin" file (which I located (9.5.30.1808_1.5MB_PRD_RGN)) or open the stock binary I read from the chip, or the patched binary. I tried all 3 and FIT gave me an error each time and wouldn't work so I never got to step 4.

    Should I get a better programmer?

    I'm just after some advice at the moment, is there anything I'm doing wrong?


    Thanks!

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