Permissions and WU problem following PSU failure

Well, it got through the first full (and slow) installation process and then I got a failed installation message when it went to restart. Back to black wallpaper desktop just as before. I had uninstalled MBAM and Windows Defender, disconnected all external drives. Bios has latest firmware. Not sure what else to do. I did go to a website about getting ready for the upgrade and one the the issues was being sure that I had admin priveledges. Will all those pemission issues I have gotten since the PSU had a psychotic break, I just don't know. I was hoping it would say what killed it. My User Acct says Administrator but some missing permissions, is that good enough?

I also tried to run setup.exe as Run As Administrator, ran the MBAM removal tool and I turned off a bunch of stuff on Task Manager. Same result.

For no particular reason, I tried to install via the USB Flash Drive. Faster but same result at the same point in the process.

Oh, also, it said it was going to restart after the updates but it didn't. Same with the USB method.

 

Anyone??
I was surprised to find really no threads for my predicament out of over 2,700 Windows 7 threads when searched as "installation failed".

 

Is that free, too?

 

Before I go through the hassle, is there a way to pretest if the product key will work? I am worn out by all this. The persistent failures with the upgrade, the black wallpaper on the desktop and generally one issue after another, it makes me wonder. How do I get the clean install version or is just a matter of not checking the "keep files, etc" option? The list of things you have to have for the clean install, too, look ominous according to the "Clean Install of Windows 10" link above.