Nov CU, Dec CU, both causing big shutdown/startup issues

November Patch Tuesday last month gave me a big issue - computer wouldn't shut down properly. It'd "Shut down" apparently but then the LED would stay on and the fans still spinning. Nothing fixed it, it was due to that update, so I rolled back and put updates on hold.

Now December patch tuesday is here and guess what.. same damn problem, but also, when it reaches the desktop upon startup, it's just blank gray. I can CTRL-ALT-DEL to get task manager but no luck.

Additionally, installing the 25H2 update hangs indefinitely at 70%. Awesome stuff microsoft!

I'd really rather not do a full reinstall, what can I specifically check to see what the issue is? I mean maybe i'm just missing a certain component.

I've already tried the classics (SFC, DISM etc) to no avail.