As I've suggested in previous threads on this topic, when the keypad is replaced or repaired it should be well sealed when mounted to the coach wall, and additionally the pad itself should be sealed into its escutcheon. They are two different entities that make up the unit. Either or both can and do allow water inside, rainwater or washwater, and from what I've seen that is a common reason for the keypad's failure, or at least it's temporary malfunction.
I recommend Lexel sealant.
Joel
Joel