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.