[Blind-sysadmins] win7 system stuck in a boot loop

Hello, I've got a win7 system that had a problem reported to me. When checking it it is in a boot loop. It's a gigabyte board if that matters, uefi bios. I am wondering if there's a way to get it to boot last known good configuration, via a setable boot flag? I've got an external drive enclosure I can put it into, take it to another box, and work, so I can set anything there. This machine by default is not set up to boot from USB drives, and I do not have sighted eyes on hand to get it so, so booting off my thumb drive is out. I'd appreciate any suggestions, with one item, I can not reformat this machine currently. Thanks. Dave.