Hi! This if my first post so sorry if I'm not abiding by certain guidelines. My Internal Hard Drive was making a clicking sound and was extremely slow to boot up. If I log in, it loads for a while, goes to a black screen for a while, then goes back to the logging on screen. I decided to replace it with an SSD that wasnt in use (Sandisk SSD Plus 240gb) and it didn't detect the drive. Afterwards, I installed OSX on the SSD in an external enclosure, no problem. After, I put it internally and it doesnt detect the OS. PLEASE HELP?!??!?