Unable to Boot

Whenever I try to boot I get an error 'Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key"

I have WD SN750 M2 drive installed for over two years. Never had a problem until yesterday. there were two older HDD's connected that I removed and added a couple of SSD drives I had taken out of laptops. I had completely forgotten that at least one of these still had the laptop OS installed, and when I rebooted, I was booting to the SSD. I shut down and disconnected the sata cables from both drives so only the M2 drive was bootable, and that's when I started to see this error.

I went back to the laptop SSD drive and deleted/formatted the M2 drive in diskpart. I then used Paragon backup recovery to put the latest backup back on the drive, and by all accounts it was a success. When I boot, I'd get an error that Windows can't be booted from this drive, but I can click F9 and see there were two Windows installations, and the only one that would load was on my external hard drive. (where I stored the backup I recovered from). I restarted the whole process a couple times, each time it worked it would only boot if I selected the OS on the external drive, but if I take that away, I get the above error.    

When I go into boot manager, it shows that all boot devices are empty.
When I go to the boot menu, Boot Option #1 shows the M.2 drive. I've disconnected every other drive from the computer except the blu ray drive, so there is only 1 drive to boot from.
I've tried disabling CSM and disabling boot manager but then it will only boot directly into BIOS if I do. I am thinking of reinstalling Windows from scratch to see if I can at least do that, but then what? I need the files on my backup for work and life in general.

Any suggestions before I go that route? Thank you in advance.