Quote from Jcredible:
Sorry. There is a black wire that is connected to the board and on the other end it has the green sensor thing i guess. Well i pulled the black end from the board off as well as the part that is connected to the board. I used some krazy glue to sit it back on the board but it was connected up there with like silver stuff.
It took about 5 minutes to boot and the fan was going crazy. Oh yeah it wouldn't shut off, so i took it back to the Apple store and i guess i got lucky. They gave me another one. LOL! Next time i will be extra careful.
Check out step 12 of the Mac Mini tear-down instructions elsewhere on this site. You are not alone.