Humminbird 997 Combo

Disconectted it to read serial number for update. When I plugged it back in a white screen kept appearing, then half white half black, now the home screen is comming up but cutting right off???

bad connection. turn off battery. unplug it again. wait 15sec.
plug it back in. Flip the battery back on.

If you dont have a pergo switch, disconnect the battery. Must have zero power when your reconnecting the unit.