data-medics wrote:
I don't know why no one is suggesting this, but if you had High Sierra on there the file system of the SSD may be APFS, in which case an older version of MacOS won't recognize and mount it.
Might not be a hardware issue or sabotage of the SSD at all.
I hope it is as simple as that!
The original poster stated it was booting with the apple bong when left at the shop and then not booting with the bong when collected.
I think they either swapped out the drive or the motherboard. Or maybe they damaged the motherboard when attempting to diagnose the problem.
Another thought is if the drive has an APFS partition then it will only be seen by a later OSX version as has been mentioned.....is that before High Sierra? Also the downloaded tools used by the poster might not be up to the job ie. not new enough to be compatible?