It's probably stuck and didn't make changes to your system. Having said that, you can't be sure you haven't bricked it, so I recommend that while it's still running right now, that you copy out of it anything you wish to backup. Even if you brick it, you can still pull the drive and recover what you need, but it's easier now to just make a network copy or to an external drive.. If you have bitlocker, either turn it off now or make sure you have the recovery key, just in case.
After you got what you need, kill the update and reboot.