This is why I don't like forced updates. The latest version from MS caused my Win 10 box to go into a endless reboot. I would turn it on, get to the logon screen and15 seconds or so the screen will go black, then blue, then reboots. I went to the DELL tools when it started up and did a hardware check and it was all good. Safe mode wouldn't tell me what the problem was, all it showed was 'hardware' failed according to the software. Rather than working on what driver (if I could even find what was causing the issue) was at fault it was faster for me to restore the machine to its original state. One of the normal tasks I had was backing up my data so that wasn't going to be a major issue for me (I thought).
I forced the system to go back to the original Win 8.1 installation and then went through the process of updating that. I have made the decision that going Win 10 isn't happening on that machine. It took me a few days to get things up-to-date and patched. Removing McAfee was a bit of a pain as even when I said to remove it I was told I didn't have the authority (I was using the admin account). McAfee did have a tool to do a complete removal and that worked. So far the machine is running very well, no reboots!
The only issue I had was restoring my email (Thunderbird). My latest backup of the mail folder didn't work, but, as I had multiple backups I could go back to an older backup. All my other documents, videos and pictures restored without a problem.
Lesson learned is that I will now have checkpoints to restore back to in the case a future update messes up the system. I turned it off thinking I wouldn't ever use it and I could use the disk space for other things.