keyboard not working, functions keys are working

only the function keys (adjusting display brightness) work. Every other key stopped working a long time ago, though I have always used an external keyboard which works. Over the years I have searched on this issue and many on Reddit have had the same problem. The solution was to restart the laptop without power cable plugged in. This was working for me but then I got really annoyed and took on the challenge to fix it by any means neccessar. I thought it was a simple bios fix, but I installed outdated bios version BHCN26WW, which bricked my laptop so I had to flash the bios using CH341 programmer, I think I flashed it to BHCN43WW or 44 don't know. It unbricked my laptop but didnt fix the issue, until I switched OFF the Turn on fast startup option from Control panel -> Power options. This fixed my keyboard and it would work enough if the power cable was plugged in, so basically it was working normally, except for keyboard backlight not working (even from Lenovo Vantage app). However, for some reason few months later the keyboard completely stopped working (aside from function keys still working).