A few days ago I upgraded a Windows 7 Professional system to Windows 10.
After the upgrade was installed, I saw a blue screen with "Finalizing your
setings" with a spinning circle of dots above it. I didn't need to use
the system for a few days, so I left it in that state for about 3 days.
But with the same message displayed today, I was able to resolve the
problem today by holding the power button down for about 15 seconds until
the system powered off. When I powered the system back on afterwards I
saw "Welcome to Windows 10!" with the account I had been logged into
before the upgrade showing and a Next button near the bottom,
right-hand corner of the screen. When I clicked on Next, I saw
the "Choose privacy settings for your device" screen, though I had made
those selections during the upgrade process previously. I altered the
selections again as I had before and then saw a "Meet Cortana" screen
where I clicked on Not now. I then saw "Finalizing your settings"
again briefly and then the screen went black. I saw the disk activity
LED for the laptop blinking rapidly for a minute and then I saw a circle
of spinning dots on a blue background above "Please wait", but then I
got to the "Press Ctrl+Alt+Delete to unlock" screen and was able to log
into the laptop where within a few moments I saw "Thank you for updating
to the latest version of Windows 10. I typed
winver in the
Cortana "Ask me anything" field and hit Enter which resulted in
winver being shown as the best match. When I selected it, I saw
the current version of Windows being displayed as Windows 10 Version 1709
(OS Build 16299.125).