Compromised BIOS

Hello I used another person's USB and my BIOS got corrupted and undetectable hooks and rootkits got installed in the BIOS.There are multiple signs like the cursor moving very slow and freezing from time to time and sounds of devices being disconnected and connected at random intervals.I have tried reinstalling Windows and also used Windows Antivirus and Malwarebytes but they can't detect those kinds of threats

Can I do something else about it or do i have to buy a new laptop? I'm on a tight budget and I'm not able to buy a new device soon by the way and I'm looking for alternatives.

The hackers that did this to me are keeping track of my online activities and device 24/7 even as I'm posting this and they delete the security logs from the windows event viewer btw