I will try this next.
I have wire brushed the earths on the wing by the battery but not sure ive done the rest. I think the next thing to do is process of elimination and remove all the fuses. As for setting it on fire i think the way you guys have said will be best lol.
just hope u find the bloody thing and cure it
meant to say it does warn not to unplug or remove any ecu system that's under the bonnet with the battery connected as it can cause damage to them
don't know how true it is, but read it and thought I would at least pass it on
plse let us know how u get on
only thing I can think of through this is the force of the water has maybe dislodged something ,it would have dried out ages ago
so something must be either touching , or dislodged somehow
everything is crossed for u
shame like I said u wernt down this way as a fresh set of eyes , etc