Check your Central Locking pump. It is located under the trunk floor behind the right rear wheel well. It is a rectangular box covered with yellow foam.
Check for signs of water intrusion. Look at the connectors to see if they have any corrosion. If it does you will need to replace it.
There are no new units available so you will need to find a good used one.
Make sure to get about 18 inches of wiring with it. Water wicks up the wire and will cause problems in the future.
Let us know what you find. Good luck!