Apparently you can get beyond the screen lock up.
Since you haven't downloaded it and haven't installed it. . . it may not be the responsible party for your screen lockups. It may be some other problem. . . perhaps some other malware that may have piggy-backed on the means MS used to send you upgrade. Apparently they are using peer-to-peer cross downloads for some of the distribution which may open the door for some mischief.
It may be necessary to restore your Windows system to your last Restore point that was clean and working fine. You DO have one, don't you?
You can try deleting the upgrade and re-download it. . .
Yes, I do have a restore point
Since I use Norton; it may not be compatible with Win10 .. even though they just sent us an upgraded version of Norton which is very nice to use. That could be the issue. Win10 may not like it. Does Win10 have it’s own -Norton Type- software ..??
So, if I get rid of the Win10 in my “MS update” folder, why would that be a problem ..??
Oh yeah; I’ve NEVER had a successful malware attack since I got my computer and installed Norton - in 1995.
And .. I don’t get viruses either.