My MacBook Pro mid-2012 has been acting up lately. A year ago I replaced the original hard drive with a Samsung SSD 850 EVO 1TB, and everything was fine. Then the SSD became corrupted and was exchanged under warranty. Since installing the second SSD I've installed a fresh copy of the latest macOS Sierra on a single 1TB partition and have been having issues ever since.
The symptoms are:
- Random fails: When I wake it up from sleep or open the lid I find it with the "grey screen with crossed circle" (Similar to this: https://qph.ec.quoracdn.net/main-qimg-b29f58e707cef6f20a882248f4ee558c).
- Fails to find a bootable volume when rebooted (or even after a shutdown and reboot) within a ~20-ish minute timeframe (boots to the folder icon with a question mark, similar to this: https://i.stack.imgur.com/V5agg.jpg). I have to wait and try to boot it again later. Then it boots as if nothing happened.
What I have done:
- Reset the NVRAM. Result: no significant change in behaviour
- Reset the SMC. Result: no change in behaviour
- Did the Disk Utility trick where I modified the size of my partition, then set it back to a single 1TB partition again, in order to have Disk Utility rewrite the partition map (or something). Result: now it doesn't constantly fails when I close and reopen the lid. Although it may have been the result of the next point.
- Changed the energy settings to default (I have a script I run when I setup a new computer, and it includes some non default power management settings). Result: see previous point.
- Does this seem like a hardware failure or a software failure?
- What can I do to be sure either way?
- Any suggestions on how I can reliably fix this?
I have several full backups of my data, so I can try virtually anything. I'm determined to find out how to fix this. Perhaps installing a stock version of macOS Sierra and not changing anything at all, and using it like this for a few days could help me figure things out in more detail?