Washed my car today, as it is up for sale and someone coming to view

After about an hour after I had washed it, when I was driving, the door open warning sign came on the dash. And then central locking is trying to lock itself on its own

The door mirror switch controls the central locking, the passenger side door mirror is moving on its own. Does the same thing with the keys out of the ignition ... Seemed to be ok when locked up. So i put it away in the garage, Incase it is something that may dry out. But then the alarm started going off after about 10 mins

Anyone experienced this and could help??

Could be water in the convenience unit inside the door ? is the door holding water as its a common fault ? cheers - Stuart