Yes, I've done "disable automatic restart after failure". The machine actually is not bluescreening. It brings up the windows logo, the white balls spin around a few times. Screen goes blank for two seconds and the logo and spinning balls come back. It goes black again about 5s later, and reboots. It never does automatic startup repair.

What happened was that I did a Windows 7 Professional x64 -> Windows 10 Pro x64 upgrade... and that's when things went horribly wrong. I've done the upgrade on three other machines and not had any trouble until this machine.

What I think happened is that there were file system errors that did not get checked before doing the upgrade (did Windows Setup stop checking the target drive for errors in recent years?). It puked out somewhere during the upgrade, and now is stuck in some horrific limbo. I've done the chkdsk /f and fixed all the errors. I've checked the SMART status of the SSD and it is in perfect health. I've rebuilt the bcd (both with bootrec /rebuildbcd and by hand), the mbr (bootrec /fixmbr), and the bootsector (bootrec /fixboot).

I've attempted to do a Startup Repair with the setup disk (the obvious choice, right?) but that's where things get odd. I choose Windows 10 Pro (not Windows 7 Professional which is still in the list) and I look in srttrail and it says at the bottom:

"The operating system version is incompatible with Startup Repair"

I'm 100% sure that this was the disk used to install the upgrade. I did not use the tray icon to do the upgrade because I don't want to have to download the upgrade files for every single computer.

Am I hosed? I'd really like to salvage the install on this computer. It's not my computer and the owner of the computer is going to start keeping backups (1TB WD Passport Ultra on the way, 20/20 hindsight, etc.) from now on. Hopefully, this is not beyond repair. Ideas appreciated.