W10 BIOS disaster, any ideas?

UEFI BIOS update is successful, but an old system hard drive I had plugged in via USB had an installation of windows on it. It UPDATED THAT! Boots up now over USB and Windows is royally confused. This was an old drive from a completely different chipset too, the X79, at least a year old.

When I remove the USB drive and try to boot to my original drive (internal). I get the dreaded error of missing the UEFI partition.
Error missing winload.efi

I made a Windows recovery USB, but startup repair couldn’t fix it. I don’t know enough about what happens during a UEFI BIOS update. Does a UEFI BIOS update make any changes to a system drive? It restarted itself like 6 times when updating.

If I can recover the internal drive, that would be ideal. Thanks for your help.

Possibly dumb question, but you’re certain you’ve got the right boot device order selected in BIOS? In other words it’s for sure pointing to the correct internal drive to boot from in BIOS…?

Yeah, that’s what I was thinking… MattiasNYC posted before I could finish typing

Maybe you installed this drive as ‘legacy’? So it won’t boot when your bios is set to UEFI!
Go into the bios and set it to legacy.