Internal disk not recognised, disk itself is not the problem

Hi everyone. I'm currently experiencing a hard drive problem on my mid-2012 Macbook Pro which I've not seen or heard of before, any help?


In brief:

My hard drives are not being recognised when connected internally. I know that the drives are good because they work fine when connected via a USB enclosure (I have two SSDs, my main and a cloned backup*). Some sort of hardware problem I guess? The only thing I could maybe try myself is replacing the hard drive cable, but is that realistically a possible solution and even worth attempting? Otherwise, I'll need to take it to Apple or a reliable independent repair shop?


More detail:

My MBP just wouldn't power up one day; all I got was either a "no entry" sort of icon or a flashing question mark directory icon. Diagnosis: no startup directory found. I reset the NVRAM/PRAM/SMC first which made no difference.

With my cloned backup disk swapped into the internal bay, same problem.

If I connect one of my disks via USB with no internal drive connected then everything works as normal.

If I connect one disk via USB and one internally, it boots from the USB and then only the USB disk shows in Finder. If I open Disk Utility the internal disk appears and the volume name is shown greyed-out below the disk, with the volume 100% of the disk capacity (correct) and free space 0% (should show 20-30% free space), and trying "Verify Disk" causes a failure. In the "Statup Disk" window I do see both drives named correctly but attempting to set the internal drive as the startup disk does nothing (no freeze, no dialog boxes, just nothing).

Running "Diagnosis" (hold D on startup) gives either error 4BAT/6/40000005: 0X8981d990 or 0X8981ef90 which I believe are battery errors. I swapped a third-party battery into the machine two years ago and it has been fine.


Thanks!


* In case you're wondering, my backup drive is an SSD because it was originally my internal drive. Something got corrupted on it, I bought a new SSD to clone onto, cleared the old SSD and cloned back and it has been fine ever since.

 

Thanks for the replies. Yes it's a non-Retina mid-2012 13" MBP, good to know that this is a known problem so hopefully the cable will fix it. I actually ordered a replacement cable last night, I figured why not just try. Maybe worth mentioning too: the sleep light is no longer functioning (always off) - maybe this is another sign that the cable is the problem?

I'm in France and work in Switzerland, will try an Apple Store if the DIY fix has no luck.

And yes, I have had SSDs in this machine for years now, I like them.

 

Update on this: replaced the internal disk's SATA cable. Cheap and easy. Now running as normal.