Legion 5 15ACH6H Invalid Serial number after reprogramming BIOS
So, for about a year I've had this issue with my Legion 5 15ACH6H laptop where the CPU fan would go from silent to full blast and back to silent every few seconds under no load at all.
Used to flash back the BIOS from GKCN65WW to GKCN52WW and that seemed to resolve it for a while. At least until Windows decides to upgrade the BIOS again.
Flash forward a couple of months. I'm in the process of back flashing my BIOS and doing a hard reset after the back flash. As I hold the Power button Windows decides to upgrade my BIOS back to GKCN65WW. I shutdown the laptop during the upgrade and brick it (stupid mistake I know).
So, I order a CH341A BIOS programmer and go to work. As I pull apart I notice that the FAN header wire in the CPU FAN isn't pushed into the connector at all, making no contact. I save that issue for later.
Eventually, I manage to flash the BIOS to GKCN65WW succesfully. I also ordered a new CPU FAN and installed it. All good!
Now, the only thing remaining is that my serial number is no longer 'linked' to the motherboard and I'm looking to restore that.
I've done some research and found a couple of Motherboard Self-Repair tools on the Lenovo website. Unfortunately, my specific Legion model is listed nowhere as compatible.
I figured I could at least try one of the other tools and use my model number as input, but to no avail unfortunately.
Now I'm here basically as a last resort hoping someone knows a way to 'reprogram' my serial number.
All help is appreciated!