k660
Forerunner
However, after a restart, I can no longer access the BIOS — though Windows still boots fine.
all of this sounds very asus-like, that is asus fast boot enabled situation. turn it off , if it isnt yet.No clue what is happening with your bios lol, you say you are able to get into windows but not bios which is weird because your PC has been able to post and reach into windows so why not bios then lol.