Leave it powered down and with the battery out on a warm radiator for 24 hours and allow the circuitry to dry out fully. Turning it on while it may still have water/ other fluids inside the device will only cause it more damage.
I dropped my mobile in the pond while fixing the pump and it was fine after a day on the radiator. You may see problems with it if you get corrosion on contacts due to the immersion though
