TPMs are basically storing the hashes of various pieces of software, then deterministically generating a key from those. Since the BIOS software changed, that hash changed, and the key it generates is completely new.
If someone had messed with your BIOS maliciously, that's desirable. Unfortunately you messing with your BIOS intentionally also makes the original key pretty much unrecoverable.
If someone had messed with your BIOS maliciously, that's desirable. Unfortunately you messing with your BIOS intentionally also makes the original key pretty much unrecoverable.