Battery flat after standing for three months. Customer jump started with jump pack. Experienced cutting out and lack of throttle response. Fault codes read: P2101 Motorised Throttle Coherence
P1631 ECU Defect (Repeated 3 times)
U1000 CAN: connection with engine ECU
U1003 CAN: invalid message from E1
P0121 Undocumented
P1041 02 Sensor Heater Circuit Rear
Codes were cleared but P2101 came straight back even before starting engine. Checked and cleaned all connections to throttle pedal and motor, ECU, body control module and all under glovebox multi plugs. Tried resetting body control module several times but the longer car was here more symptons started appearing - wouldn't start at all at times, fan (Rad) kept coming on and off at various speeds and durations, throttle would operate on its own and surge. Also new random fault codes kept appearing: Evap Purge Valve, more throttle and ECU codes etc.
Finally managed to clear all codes and seemed to be running properly but within 3 miles of road test it just cut out at traffic lights and wouldn't restart at all.
Think it's either a body control or ECU problem but how do we confirm which it is?
Also on live data fan is not shown to be operating and no fan request even though it's running.
Immobilizer and ECU programming is all showing as being OK.

Any thoughts?? Many thanks. John