........What happens when you plug the motor into the wrong two holes of a Parkzone UM T-28, WITH THE BATTERY PLUGGED IN.

Ow! Ow! Ow! Nothing major, just a harsh reminder, unplug the battery when working on your plane.
Situation: Just put lights on the plane, was testing the lights, with the TX OFF, and decided to put the plane back together. I plugged the motor back into the wrong 2 holes of the RX and the motor and prop went full blast beating up my forearms. Just some sting and red marks. Glad it wasn't anything bigger.