macbook pro Hard Drive Cable
The hard drive was showing signs of getting old with erratic behavior until the day it stopped completely. The machine would not boot.
I thought it's the hard drive but when I tried to recover data I realized the hard drive was perfectly fine.
Then by looking on the internet I saw that this cable is often getting damaged.
Quite easy if you can screw/unscrew very little screws
Don't be afraid, get your hands dirty