Neff U1661N0GB/01 Main oven elements not working.

I had a call to the above oven as none of the elements would get hot in the main oven following being professionally cleaned. Apparent the oven lamp had blown and been replaced by the cleaner.

I found an earth fault of 10 megohm in the grill/upper element and the relay that supplies the live to all the main oven elements not working.

I have read in a couple of threads n the forums that these control units can blow following a light bulb blowing but what doesn’t make sense if this is the case is, as the oven lamp was replaced this now works.

I would have thought if the main oven lamp caused the control unit to blow then would that not have blown the part of the circuit that supplies the lamp?

Can anyone say if this is still likely to be the control unit or if it’s something I’ve missed?