Simon, you're right about the switch reset for when battery is flat or disconnected (Dealers explain this at delivery) but the problems in the original post seemed to affect everything controlled on the steering binnacle, wipers, lights, etc which has been one of the S4 electrical issues.
I've just looked at the instructions and the thing I call the shorting plug is in fact called the VBC shorting plug and the instructions sheet is titled 'Instruction to Re-Boot System'
