I don't remember it downloading an update but normally it does this when it updates, so maybe one was d/ling in the background? I restarted the laptop because it was running slow and normally that fixes it. But this is the longest time it's ever been hung up.
Its basically a window over your desktop you can press ctrl alt dlt I'm sure and it opens the task manager. Check if there's any processes doing anything and if not probably fine to reboot
Ctrl + Shift + Escape is the new task manager combo. Ctrl alt delete brings up a list of things that includes task manager but that might not work mid-update because it's the same window.