MacBook Pro Hard Drive Cable replacement....a five minute repair
Hard drive would not unmount, the MacBook Pro would either boot to a gray screen or keep freezing when it did boot. A new drive did not solve the problem. I was told it was probably the logic board, when I realized it was in fact a simple fix, I went for it.
Ifixit is always my go to site when I have problems with any of my Macs. The repair photos and directions were right-on. I purchased the part from them directly since I knew I would be getting the right part the first time. Ifixit listed it as "Moderate Difficulty"...should have been "Super Easy"!
Trust Ifixit, trust their directions, trust their parts. Don't give up when it looks like your item may not be worth repairing. Do some research, log onto Ifixit.com and do it!