Me too - standard Dell laptop running Win 7 and it just hangs (for over three hours) with a blank screen and no disk activity.
I restored from an image, checked the disk, uninstalled some stuff, tried again, and exactly the same problem.
And when I do a hard boot afterwards - it just goes straight to the same blank screen where it will remain forever.
Complete waste of a day.
Why didn't the programmers get it to realise a failed installation on reboot - and offer the option of recovery?
I'm advising all not to touch Win 10 without a pre-image and only if they have 5 hours to spare !