Unplug anything plugged into a USB port.
Lock your car. Wait about 3 minutes.
Unlock your car, get in, put your seatbelt on.
Press the ON button for a full 2 seconds with the brake pedal pushed.
Now if the screen wakes, wait until the NAV comes on completely. That is the last item in the boot sequence. It boots:
Climate
Phone
Music
NAV
Lock your car. Wait about 3 minutes.
Unlock your car, get in, put your seatbelt on.
Press the ON button for a full 2 seconds with the brake pedal pushed.
Now if the screen wakes, wait until the NAV comes on completely. That is the last item in the boot sequence. It boots:
Climate
Phone
Music
NAV