I tried to downgrade my Y540 to an older BIOS because the newer version was causing me problems with thermal throttling. The installation went ok at first, but after it was done, I did not get any video when powering on the laptop as I managed to corrupt the chip.
I sent the laptop to Lenovo, they did not try to reprogram the BIOS chip, and instead, they told me that the whole motherboard needed replacing. I got the laptop back from them, unfixed, and tried to program the chip with a CH341a. I managed to fix the laptop after flashing the newest BIOS; however, now the laptop does not have a serial number on the chip, and the motherboard shows up as “INVALID” in programs such as CPUz. Because of this, I can no longer use the Lenovo Vantage software as it doesn’t know which model I have.
Is there any way to add the missing information to the BIOS either by modding a BIOS or by using some sort of programming tool? I do not know the technicalities of BIOS modding or programming and any help would be appreciated.
Thanks 
[Solved] How to extract UUID from a corrupted BIOS Backup?
If you backed up your corrupted bios, you can restore all the DMI info by modifying the bios file and reflash it byCH341a.
But if you did not, it seems impossible to fully restore the info, but may be possible to restore some. Google LVAR tool.