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    T420s won't downgrade BIOS below 1.12

    Discussion in 'Lenovo' started by bogatyr, Jun 28, 2011.

  1. bogatyr

    bogatyr Notebook Evangelist

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    Has anyone been blocked from downgrading their BIOS before? My custom ordered T420s came with BIOS 1.24 (not on website yet) and will only downgrade to 1.12. My preconfigured work T420s came with 1.12 and goes down to 1.05 just fine.

    When I try to do it on my custom T420s the error is:

    Only BIOS files for 1.05 and 1.09 give me that error, 1.12 and 1.13 work and I can't try going back to 1.24 since it isn't available and I didn't care to back it up.
     
    bogatyr, Jun 28, 2011
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  2. bogatyr

    bogatyr Notebook Evangelist

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    I was able to downgrade today. Lenovo's tech support from Atlanta called me back after putting in a request using ESC+. Their suggestion was to use:
    how to downgrade BIOS

    Which doesn't work as the flash app works a bit differently.

    The steps that worked for me:

    1.Download the 1.12 BIOS and the 1.09 BIOS.
    2. Extract both to their respective folders.
    3. Copy all the files from the 1.09 BIOS folder except WINUPTP.EXE into the 1.12 BIOS folder.
    4. In the 1.12 folder, delete all files in the 8CET35WW subfolder
    5. In the 1.12 folder, copy all the files in the 8CET32WW subfolder into 8CET35WW subfolder
    6. Run WINUPTP from the 1.12 folder
     
    bogatyr, Jun 29, 2011
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