If the phone has fallen in dirty or salt water, rinse in distilled water. Then shake it in order to drain and put it into a small bag. Pour ethanol 96% into the bag. The alcohol will displace the water.
The circuits will be alcohol wet instead of water wet. Alcohol doesnt rust the circuits like water does.
Now try to remove the alcohol. Put the cell phone on a heater that you can stand with your hand, not very hot.
Other option is to dry the phone with a fan or better to use the vacuum pump system that is explained here: http://www.youtube.com/watch?v=rg6RhUOQ278
This is a last chance procedure, so do it at your own risk. I assume no responsibility.