Update fix
Tony thanks for info, found the capacitor under the nearside wheel arch liner, no damage from anything. I had left the battery off all last night and came to car this morning did a check of all the wiring and connections with ref to unit and the stop start, pulled and pushed all wires didnt find anything much. Put it all back and connected battery and on start up all ok, retested a number of times and still ok took it for a run and still ok a bit of a puzzle