That sounds pretty much like I do, except I don't wait the 15 minutes and just use the switch to cycle the power about 1 minute after getting the 100% complete message.
The suggestion above to skip the auto update and do it manually might be more reassuring as cycling the power always seems a last resort.
@ByJings I waited 15 minutes because mine just got stuck on Updating and didn't go any further
I’m sure you’ve already found the resolution to this problem but I’m leaving this for the benefit of anyone in the future visiting this in the future. All i do is unplug the box for 1 minute and reply back. That’s it.
The box now seems to install updates and restarts automatically without any issue.
Perhaps one of the many updates fixed the problem.