Windows 10: No Login Screen and No Power button

Hi.
Not to butt-in, but just wanted to mention this:
I have seen many a problems with W7>W10 upgrades, many of which are near impossible to troubleshoot & fix; all of which were corrected by a clean install of W10. For some reason, it appears that W7 upgrades just carry too much baggage with them (unlike W8 upgrades). Something to consider at this point.

 

I'm leaning toward the clean install as an ultimate repair. Hopefully, you have a backup of your wife's desktop PC so you can recover her files. If not, you'll probably want to buy a dual drive caddy (something like this: VANTEC NexStar TX Dual 2.5HDD Dock) so you can remove the drive with the bad install on it, grab another drive, and copy the contents of the damaged install onto the other drive. Then, you can proceed to clean install Windows 10 on the old drive, knowing that you can get to the files on that drive if you need them later on. Alas, however, this will not rescue the applications installed on your wife's PC: you're probably going to have to do all that stuff over. My apologies for the inconvenience.
Best wishes & HTH,
--Ed--