This is very interesting... Thoughtfix's picture of the open N800 shows the charger isn't even soldered to the board, it is embedded into the plastic back of the N800, and it just has two contacts that press against the board... So if that board gets separated enough from the charger port, it would stop making connection and stop charging... Try pressing the charger port upwards (towards the "face" of the N800) while the charger cable is in the port and see if you get any response... maybe just pinching that area while the charger is in...? very interesting...