MID-2012 MACBOOK PRO HARD DRIVE CABLE REPLACEMENT

My father used an old 2012 MacBook Pro as his personal computer for financials and general use (he thought the family laptop was virus-ridden, which probably had some truth to it). On Saturday, he called me down from my room because he got a windows BSOD (Blue Screen of Death) error. I quickly ran down to see if I could catch a glimpse of the error code before it went away, but I couldn't. My dad also didn't read it in time, but I thought it was no big deal. He tried to turn on the computer again, but he was greeted by a weird screen that looked like this:

Essentially, this means that there is no hard drive to boot from. I kept trying to boot, and I tried to run recovery mode (⌘ + R while pressing the on button). Eventually, I came to the conclusion that the problem wasn't software related - it was hardware related. I removed the hard drive and plugged it into the computer I built, and the drive was detected - I was able to see all the files (Paragon HFS allows you to see mac formatted files on windows) on the hard drive. I searched for solutions until I came across someone stating that their hard drive cable was the problem.​ We bought the hard drive cable from http://http://a.co/9MTV5cP and I replaced it. I'll write a step-by-step guide below.
Note: The screwdriver I used can be found here: http://a.co/1XGGO9R . It worked very well, and can be used for a hard drive replacement.
1. Turn the macbook on its back and unscrew the screws. Diagram:

2. Remove the cover and unscrew the two screws on the bracket. Diagram:

Detach the cable from the hard drive.
4. Detach the cable from the motherboard.
5. Unscrew the screws that connect the cable to the computer. Diagram:

6. Unscrew the black bracket is close to the edge of the MacBook.

7. Pull the bracket out and remove the cable from the MacBook.
8. Using a flat head screwdriver, pry the orange cable away from the bracket.
9. Remove the black part from the cable. Diagram:

10. Completely remove the old cable from the Mac.
11. Take the orange part and put it on the black part of the new cable like on the old cable.

12. Screw the bracket back into the place it was before. Diagram:

13. Remove the adhesive from the new cable and stick it down along the path of the old cable.
14. Screw the cable into the Mac. Diagram:

15. Plug the square connector from the cable to the motherboard.
16. Plug the hard drive into the other end of the cable and set the hard drive down.
17. Set the hard drive back into the hard drive space.
18. Put the original bracket back where it belongs. Diagram:

19. Screw the bracket in. Diagram:

20. Put the back on the Mac.
21. Screw the screws back into the MacBook Pro.
22. Turn on the MacBook Pro.
23. Success!!

Hopefully this helped you replace the hard drive cable on your MacBook Pro. This worked for me, and I finally stopped getting the folder with the question mark.