I would do the CLA thing, and DO NOT APPLY HEAT! I have a history of dropping expensive things into the water and now own a lot of even more expensive waterproof things. One lesson I learned is to remove moisture with dry cold, or better yet a vacuum chamber. The faster you can get it into dry cold or a vacuum chamber the better. Heating will actually accelerate rust formation (at least it feels that way) and may damage things that are not broken now. You are going to want to get a CLA to be sure no metal parts have rust on them, and to clean and re-oil the ones that are at risk. Rust never sleeps or stops unless treated, let the shop know your camera went for a swim so they know to disassemble and clean everything. It may cost you, but think of it as an "educational expense".

Good luck.