After some hickups, I was able to do the upgrade. The MediaCreationTool is what I used. I tried first to launch the update via Windows Update. When that didn't work, tried to ISO method. When that didn't work, tried the USB method... When that didn't work, I tried the "Set everything to 'Murica and do the upgrade using the MediaCreationTool"... and when that
did work, I became a happy IT guy running Win10