Flashing Folder With Question Mark???
20 - 30 minuten
Over the course of several months I had four MacBooks of various ages stop working. All I got was a flashing folder with a question mark. So, I went to the web to find out how to fix it. I found all kinds of articles telling me the files were corrupted so re-image the drive, or the drive is bad so replace that, or it must be a bad logic board which was too hard to find or too expensive to be worth it. No one mentioned it could be the data cable. When the fourth one failed and I tried a SSHD drive it showed up for a minute then failed to format. When I searched for that problem is when I started seeing articles about bad data cables.
I looked for the part and found iFixit first but they wanted $45 so I wound up ordering from another source for $20. The problem with that was I later realized it could take up to a month to get that part since it was coming from China. I went ahead and ordered a second cable from iFixit which arrived in four days at a total cost of $44.95 with shipping. The old cable came out and the new cable went in with no problem and it is working just fine.
If you've got a 3-5 year old MacBook Pro and get the flashing folder with question mark on startup, pull the drive and connect it via a USB adapter. If the MacBook boots OK order the data cable. I've since replaced the cables in the other three MacBooks and it fixed the problem in all of them.
iFixit prices may be higher than you can get elsewhere but the parts arrive quickly and they provide very nice guides which make any repair easy.