This was an email question that I re-posted on the R.A.M.P.S news group since we see quite a few units that are destroyed by water immersion each year. Below is the reply which also talks about salt water immersion. (VERY BAD. Get the battery out immediately)

Hi David,
Some of the following doesn't apply to you now, since it has been a while since the unit fell in the water. What you have done so far is OK.

Get the battery out of the unit as quickly as possible. Turning the unit off is not enough. Wash the unit with clean or distilled water. If it fell in sea water, wash it with any water that has less salt in it than the sea water.(If there is nothing better available, you can even use Diet Coke or a dry martini, shaken not stirred). Vodka or other alcohol that doesn't have lots of additives in it can be used in a pinch also. In fact, an alcohol final rinse is a good bet anyway, both to promote faster drying and to clean off any dirt or oils that may have been in the water. Tilt the boards so that the alcohol runs off and doesn't puddle around the tiny adjustment pots. After the final rinse, shake the boards to remove the alcohol or water. Then warm the boards to drive off the residual water left from the water or alcohol final rinse. Hair dryers, light bulbs, warm oven, engine block, sunlight, heater vents, etc. As far as the maximum temperature, as long as you can firmly touch the components and not quickly feel pain (140 F) you are OK. After several hours or more and the unit is bone dry, put in a battery and try the system.

In fresh water with the battery in the unit, you have a few minutes before serious damage results. In salt water, with the battery in the unit, it is a matter of seconds. Get the battery out of the unit as quickly as possible. If it fell in sea water, don't bother opening the unit to wash it. Plunge the entire unit with the battery door open into water or alcohol. Or pour water or alcohol into the unit and slosh it around. Then do it a second time with a fresh batch of water or alcohol. Then you can open the unit and do a third rinse. Inspect the circuit traces for corrosion. If there is any corrosion, try to rinse it off and/or brush the corrosion away using a stiff brush moistened in alcohol such as a cut down acid brush or a toothbrush. If it has corrosion, it may need to come back to the factory. We usually end up replacing the circuit boards or exchanging the unit completely but there is no harm in cleaning it, drying it and firing it up. Best of Luck