Chosen Solution
The video in my older Macbook Pro died. My son has a newer 2012 Pro but his hard drive died. I took the working drive out of my Pro (OSX.10.11) and put it in my son’s machine. His Pro won’t recognize the drive so I can’t even see it on Disk Utilities. When I boot the machine you hear the hard drive spin up and a few minutes later, it spins down and the question folder appears. I can boot it from my bootable partition on my external backup, but how do you reformat a drive that is not recognized by the OS?
The hard drive I/R cable is most likely the culprit. Apple was even replacing it for free for a shorty period. When replacing use something to pad around the cable as it comes onto the optical drive. I use 3M extreme mounting tape. MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement
