I am facing the same problem now... Its been now 2 hours. What should I do ..? If I follow your resolutions steps will it erase all my data's in it. I have too many contacts, photos and documents inside...
Iam in same situation as yours... I tried to update my android phone around 1:15pm and it is still " Installing system update..." and now it is 2:00pm.
How can I reboot with out losing information? How long it will take to complete ? Do I need to wait to complete ?