A Porsche Boxster with electrical failure of its total system was presented to me. Upon investigation I found a very wet floor under the passenger seat where the electronic control unit (ECU) is situated. I quickly identified the cause of the problem as being water damage. See photo 1. I removed the ECU and its casing to reveal a heavily corroded circuit board. You can see just how corroded the area on the right is. See photo 2. Through further scrutiny, I discovered the drain vents situated under the rear panel of the convertible roof had become blocked with debris and required clearing out. These vents are only visible when the panel lifts up when the roof is being opened or closed. See photo 3. I allowed the circuit board to dry out in a warm room over a period of a week before refitting it back into its casing, ensuring the floor of the car was completely dry before re-installing the ECU. The majority of the electrical systems worked after the ECU was re-installed, although the corrosion had caused irreparable damage to part of the circuit board. This meant that although the car was safe to drive some electrical systems were not working, such as the electric windows and central locking, and consequently a new ECU had to be fitted by a Porsche centre which we arranged for the customer.