Disclaimer: The BIOS should be the exact same which Lenovo published on Google Drive (state of 30.12.2020) but is (along with the guide) supplied without any warrenty. I am not liable if you brick your Laptop!
💾 Mirrored files: c940-betabios.zip
Download the mirrored files from the link above and extract the ZIP-archive.
Set up a USB stick with a single FAT 32 partition.
Unzip shell file.zip. This archive has the necessary files to boot your Lenovo C940 to a state that it can load the BIOS file.
Copy the resulting files and directories to the USB stick
The BIOS itself is in C940AudioTest.7z.
Use 7z x C940AudioTest.7z to unpack this archive.
Copy AUCN57WW.efi to the USB stick.
Turn off your C940.
Use Fn + Power Button to boot in to the NOLO (sp?) interface.
Press ESC to skip startup.nsh. (You only have about three seconds.)
Input fs0: to go to the USB stick directory.
Input AUCN57WW.efi to flash the new BIOS.
Source: https://bugzilla.kernel.org/show_bug.cgi?id=205755#c59
Alternative mirror host: https://cloud.libre.moe/s/3H3CMZxrFdTQcJ9
You can use these checkums to check if your download is identical to the files I uploaded. Please verify that the checksums are identical to make sure your download was not corrupted.
| File | MD5 | SHA1 |
|---|---|---|
| C940AudioTest (BIOS).7z | 8394a5cd417afce674a11ee7baad18a7 |
a54419d7c9682dbe6817990763bc1100b7792a83 |
| shell file (flash tool).zip | 15d6a99d4d279f28948279fe605d59c5 |
983474708085b0eca1e824e6d1501cdc21066fa0 |
These checksums were generated using Dolphin v22.04.01.