I put a backup harddrive in my computer and the computer wouldn't see it. After two harddrives I concluded that I had a bad harddive cable.
The swapping out the cables was easy, but have small hands with you to help you connect the led light cable. The install was painless and really easy. New cable worked fine.
When you swapping out the cable make sure you clean the surface of the old glue. It makes it easier to have the new cable stick to the surface of the machine.