[pjv]

Had an experience like this many years ago with my 3 litre BMW saloon. Was in the mountains in the ski season, had the car parked on a steep slope, nose upwards, when there was a torrential downpour overnight. Next morning, came out to find about 4 inches of water in the back of the car, and the engine ECU was under the back seat, fully submerged (door seal had leaked). Had the car towed to the resort garage, who told me that the ECU was dead for sure. In desperation, I took the ECU back to the ski lodge, dismantled it, dried everything in the lodge kitchen oven on low temperature. Reassembled it, reinstalled it in the car. To everyone's amazement (mine included) it started as though nothing had happened. I drove it for another couple of years trouble free until I sold it. I suppose the ECU survived because it would have been an analog unit at that time, and I did not put any power through it.