Just writing to inform I managed to fix the bios. I understood what needed to be done thanks to post #10 and #32 but the reason I was asking for help was because I had flashed before without backing up and my tools at disposal was a raspberry pi, which limited my capacity to copy the segments of bios needed as I didn't have a full understanding of this process in linux and found it very difficult to fix the file by myself. Nevertheless I figured it out with chatgpt, using FlashRom and jumper wires. Thanks....

I managed to flash the bios, but like I stated, I am using a raspberry pi with raspbian and can't access a windows computer to follow all the steps and edit the values required for my specific bios, which is why I was requesting help with the edit and supply of the customized bios with values I provided. I flashed anyway with the bios in post #10 and could unbrick it but now it says invalid mtm and sn, no dpk... If anyone can still help out providing the edited file for me, I would greatly appreciate it. Again:
Legion Y540-15IRH ModelName: 81SX S/N: PFIP2KM7 MTM:81SX000FUS Mfg Date:19/05/22...

Hello guys. New here. First I wanna thank everyone, seems like a great helpful community!

So I am having an issue with my Legion Y540-15IRH Laptop - 81SX laptop exactly as described by most. Bricked the bios, downgraded to a version that leaves me with a black screen, keyboard lights up for a couple of seconds, logo and fans on. I made the mistake of installing a bhcn21ww I found online through windows, and unfortunately didn't create a dump file or referenced my s/n mtm, etc I am only learning about all that.
I currently don't have access to another computer to follow all...