WOW! I had one of those last week and it stayed up so I did a hard kill(just powered it off with the switch)on the computer and it came back up. Ran my usual daily scans after I restarted it and nothing was found. Usually WND is pretty reliable. But it was the same thing you described. Mouse wouldn’t work and alt-ctr-delete didn’t do anything so, power switch. Sorry. Guess my default when I get one again will be to go straight to the power switch.
I killed it with the power switch too since I couldn’t do anything else. Guess I got lucky - laptop finally powered back up ... yay!!
Ran every scan I had and nothing came up, so that’s good for starters! Haven’t been back on my browser yet .... may uninstall & then install it back. I need to do a little research first - my initial searches showed folks having trouble getting rid of that screen, kept coming back.
Glad your problem resolved & I think I’m on the way to getting mine cleaned up & going. Fortunately, I do run backups & had a recent one, so that wasn’t a concern if the laptop was truly dead.