Papahuhu

Hi
Having a baffling issue and wondering if anyone can help please as I'm baffled.
Had water ingress into diversity antenna enclosure and significant corrosion to the circuit board and resultant remote locking failure. Tried to clean/repair but too far gone, so replaced it with salvaged unit.
Everything ok for about a week, then remote failure again, found more water in pcb enclosure. Got to it quickly so no corrosion, cleaned and dried it, silicon greased around enclure and worked ok for about 2 days then died.
Checked enclosure again, this time no water ingress, however removed board and dried it for 48 hours. Replaced it and it now works for 3 hours before it dies. Been through the removal and replacement cycle 4-5 times. The thing I find odd is that the longer I leave it out of the car the longer it seems to work for when I replace it.
Driving me nuts as it seems there is a time based element to the fault.

Just to add that the car has not been moved, no loose/broken wires evident and I'm 100% sure there's no water getting to the board now.

Any suggestions would be very welcome, thanks in advance.