You may be able to mitigate any damage the water could do in there by flooding the box with WD-40 and then draining it again. While WD isn't conductive, it shouldn't interfere with the relay point's delivery of current because it will readily flow and drain away from them.
At the same time, WD-40 displaces water and will also act as a mild lubricant as well as slow, if not entirely prevent, oxidation from taking place. I've used it for years to dry out wet car ignitions after they have driven through water. The effect is immediate and impressive with cars that would only crank but not start to starting and running right after having been "treated".
Just an old trick that I thought you might use to your advantage in this case.
Good luck