If they ‘effed’ with your BIOS you either wouldn’t be able boot, or have a bootkit installed.
Only advice I have is to swap motherboards and run a clean wipe on your hard drive disk, unless you can somehow find out how they ‘effed’ with your BOIS, then you should run a live distro of kali, parrot, or tails and un'eff' it up.
Start by getting the BIOS version of your motherboard.
Other questions you should ask are “why do these people have access to my device?” and “did I press Win+L?”
Jk Jk