Arthur, just like any other phone or device that has been submerged, the first thing I would do is to disassemble the phone. Take a look at [guide|9413|this guide] to see what needs to be done. Once you remove everything, I strongly suggest that you clean it, use [guide|5825|this guide] to see how to clean it. The guide was written for a iPhone 3G but all the points apply to your phone as well. Make sure that you take a very close look at every connector and see if you find any corrosion. You may have to repeat this a couple of times. Once it is properly cleaned '''replace the battery''' reassemble and re-evaluate.