Sound slike the seal has gone or he has been using a jetwash to clean the car. It is a case of taking the whole lot off and replacing....but replacements are not so expensive if sourced well.
There should only be 4 nuts holding the clusters in. Disconnect the wires and take it out. There are numerous drain holes behind it which easy block. Put the light housing on top of a towell on a radiator for a few hours and it should clear.
While it is out just check to see if the contacts to the bulbs are ok. I kept getting bulb fail warnings even though the lights DID work! As I could see where it had been arcing (due to some corrosion) I narrowed it down to a poor contact giving a false reading.