Why does the screen show a blinking picture of a "file" and "?"

You are facing a known issue with either the 13” or 15” models. The HD SATA cables tend to degrade from rubbing along the rough surface of the aluminum uppercase. Here’s a bit more Your Hard Drive Cable Is A Ticking Time Bomb

What makes this hard to wrap your head around is the drive appears to be working! You can access it so how could the cable be bad? Think of it this way you are in your car and you take a dirt road before you know it you find you can’t get any further down the road as its to rocky. But you did manage to get down a good piece so you know your car is working its the pathway thats messed you up! Thats the case here its not the drive its the connection to it thats failed.

So let’s get your model info so we can guide you to what’s needed!

Here’s the guide you’ll need to follow MacBook Pro 13" Unibody Early 2011 Hard Drive Cable Replacement, but we want this cable MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable as its the better designed cable.

Besides replacing the cable you want to place a stip of electricians tape on the uppercase when the cable crosses over. And lastly you want to use an old BIC pen ink straw as a forming brake to help you shape the needed bends in the cable Don’t crease it! As that damages it. Using the ink straw will give you the needed arch around its radius.