Have a C5 in for repair where the electronics had become 'fried' The control box was salvageable however the ULA chip in the POD had a hit and the motor load indication is duff - This week I have repaired several control boxes and pods showing the same symptoms as this one so a word of caution if your using battery tops with key switches - the positive and negative terminals on batteries can swap place - see attached photo of the battery top fitted to the battery on the c5 in for repair :
You will see that the blue wire (negative ) is going to the right hand side of the battery
Now with the top removed you will see that the right terminal is positive ! - Result control box and POD burnt out in the switch of a key -
Pod damage ::::
Hope this helps when purchasing batteries
Radiomarty