KitKat 4.4.2 error 'unfortunately, the process com.android.systemui has stopped working On Android KitKat 4.4.2 an error comes up 'unfortunately, the process com.android.systemui has stopped working.

Now I can't turn it on or off as the error keeps popping up and won't let me do anything.
I finally found out that holding the power button down turns it off. Hopefully this will help others.