This is why every machine I manage has a second boot option to download a small recovery image off the Internet and phone home with a shell. And a copy of it on a cheap USB stick.
Worst case I can boot the Windows install in a VM with the real disk, do the maintenance remotely. I can reinstall the whole thing remotely. Just need the user to mash F12 during boot and select the recovery environment, possibly input WiFi credentials if not wired.
I feel like this should be standard if you have a lot of remote machines in the field.