MacBook Pro will only recognize one specific internal hard drive

[doubleohkevin]

I'm working on a friend's MacBook Pro that would start to a flashing folder with a question mark. The directory was out of whack, so I repaired that. Then found out the hard drive is physically failing, so I cloned everything over to a new drive. I still had problems with drives being recognized internally, so I replaced the hard drive flex cable. Still no go.

Here's the situation I'm facing at the moment:

• I have four bootable hard drives to play with: the old and new drives that belong to this computer and two of my own.
• All four of the drives boot via USB.
• Only one of the drives (one of my own) is recognized when installed internally (Disk Utility doesn't see the others). That drive works consistently. The others aren't recognized at all.
• I've tested three of the drives in another computer (installed internally) and they all work fine. I didn't bother to test the one that's failing.
• Internal hard drives are getting power.

The drive that works has Sierra installed on it. The others have Mavericks or Yosemite. Correct me if I'm wrong, but that shouldn't be an issue, especially considering Disk Utility won't even see the other drives.

The new hard drive cable could be a dud, but then why would one drive work consistently? The only other thing I can think of is a bad logic board. But again, why would one drive work consistently?