Going through Windows 10 update purgatory. I had an older build, MS said it will no longer be supported, insisted on installing an upgrade.
Installation was hosed, eventually it got to the point of a corrupt boot file.
Probably 6 hours of time yesterday mucking about with restore disks, etc. None of this was "hard", simply time consuming.
Today I finally found something buried in ms tech support files that involved going in and changing attributes of bootrec, then recreating stuff.
Now the pc boots cleanly, I'm trying a fresh upgrade-in-place (via the Microsoft Media Creator Tool), seeing if it'll apply okay.
Wish me luck [emoji5]