Hi @mamf ,
Here’s a link that shows how to replace the date and time battery in your camera. It is a CR1616 lithium coin cell battery - example only
Hopefully it is only a battery problem and that the water has not caused more problems such as corrosion of the electronic components in the camera. (Check the date and time battery terminals in the camera to see if they are OK, i.e. bright and shiny and not showing signs of corrosion)
If replacing the date and time battery does not fix the problem, the camera may have to be opened and inspected to see if there are any other problems.
Here’s a link that explains in general what needs to be done.
Electronics Water Damage