KB4577671 was automatically downloaded and attempted to be installed without me realizing it. After this was done, I was prompted to reboot Windows 10 Professional. Upon rebooting, my workstation gets stuck in a non-stop reboot loop. This update is the cause of it. This happened early in the morning, and I had enough time to restore my last full backup that was less than one month old.
After restoring from backup, I successfully logged into Windows 10 as expected. Here's the thing though-- even though I have updates paused in my backup, they become enabled right after a restore. Windows 10 does this automatically. I started to update my software then shortly checked Windows update to see updates being downloaded. I immediately paused them. However, it seems I paused too late, because in this short time Windows update again mangled Windows 10 boot. There were several updates to install, and Windows update managed to break my system boot very quickly.
This reboot loop is non-stop. What I had to do was use my bootable Windows 10 install DVD to attempt a repair. I then restored to prior to the Windows update. This is when I faced issue #2-- restore points do not repair Windows update breaking Windows start-up. Even after reverting to this restore point, I was still in a boot loop!
I had to perform a full image restore yet again. When this finally completed, I again logged into Windows 10 then immediately went to Windows Update to pause updates while it was still looking for them. It took a very long time to undo this mess created by Windows update.
Here is what is not going to work-- downloading the latest full Windows image, because Windows 2004 fails miserably to install. Since I absolutely cannot log into Windows due to this boot loop, Windows telemetry has no way of sending this failure to Microsoft for investigation and repair.
Oh boy. What a mess.