reboot and select proper boot device

Is that new mobo made by Asus or Asrock by any chance ?
Asus makes some nice mobos, but it has by far the worst boot implementation of them all, and not remembering to boot from an USB is utterly disappointing and aggravating.
Now I have to ask, did you by any chance put that drive on a computer that also had a windoze drive in it and boot windows ?
All windows versions have a tendency to fix things that are not broken but they don't understand, usually prompting that the drive is not formated and offering to format it by a single click, sometimes even during boot procces they will write data to drives at a whim that there is something missing for the boot operation.
On older systems you might also check the bios and set the hard drives to auto detection.
There is always the possibility of restoring the drive after such mishaps by using a linux computer and testdisk, except formating that will be very hard to impposible to restore.
Another thing to check is can you hear the drive spinning up when powered on, and the heads being released from park and moving to the platers. Those are very distinct sounds and can be easily heard in a quiet room.

John,

Send the drive back to me and I'll either reload it with LinuxCNC or replace it.

JT

No problem, we'll get you up and running.

Which Asrock motherboard do you have?

JT

Not sure, but I think I have 2 of those with celeron processors , one of them is running a bit industrial Esab plasma cutter for quite some time now using a 6i25 and a 7i77, and the other is happily mining ethereum with two Nvidia 1060 6GB cards for over 4 months now. Will check tomorrow.

I'm sure I have a H97M Pro4 somewhere as well, it should just boot up... I know I've seen the box but which machine is it in lol.

JT

Your hard drive was here when I returned home from a short vacation and sure enough it won't boot up. Well stranger than that my master hard drive won't boot up either for Debian 9 64bit so now I'm wondering if my new disk copy device has messed them both up??? In any case I'll make sure you have a drive that boots up and get that back to you ASAP.

JT