Popped in a newly initialised (MacOS Extended) Crucial 2tb drive into my Mac Mini today and decided to do a clean install. I then booted from HS USB Boot drive, and wiped the Crucial drive into APFS (I was unaware it would do it as part of the install process). It began to install, got to the end of the 8 minutes, right at the end of the bar and then went blank and hung with a blank screen. So I restarted and took out the USB boot drive, and now it shows a folder with a question mark, which suggests the computer can't find the OS. Is it possible that the new SSD could be marked as non-bootable somehow? You used to go into Disk Util or something and mark which drive you wanted to boot from. I assumed since a) it was installing a new OS, and b) there is only one drive, that it would boot from that drive. I just booted into recovery mode and I'm on the Mountain Lion recovery screen. Any suggestions?