How do I verify that a pc/laptop has a legitimate and not tampered uefi and/or bios? Let's say I was doing somethings which potentially could be dangerous. I have inserted some unknown hard drives or flash drives and booted from them. I could run certain untrusted programs under windows or linux providing administrator or root access. I could have received a hardware from untrusted seller/source.
What steps do I need to do to check that my bios and/or uefi is not tampered before installing Ubuntu?
Is enabled Secure boot guarantees that I can trust this PC/laptop?