did win 10 upgrade on Lenovo T500 from Win ultimate. System installed. Booted. Ran a few SW installations (firefox, Classic Sh

[Not so much]

Windows 10 reboot black screen with blue window circling dots forever

 

[Colif]

Download win 10 installer from: Win 10 media creation tool

change boot order so USB or DVD first (which ever you made), Hdd second
boot from installer
on screen after language choices, choose repair this pc, not install
choose troubleshoot
choose advanced
choose start up options
choose one of the three safe modes, pc will restart and should load safe mode.
you don't have to do anything, just restart.

If that doesn't fix it, try reloading into safe mode and maybe uninstall the last thing you added and see if that fixes it.