In the past I have fixed problems like this by:
1. Removing the battery ASAP.
2. Carefully removing the PCB.
3. Rinse it all thoroughly in fresh water.
4. Either leave it to dry naturally or use a hair drier.
5. When you are sure that it is **completely** dry, even under the components, reassemble it.
6. Insert the battery and hope for the best.
If it has been left too long before rinsing, the contamination may be very difficult to remove. I would not advocate leaving it to dry out first.
BVQ
December 2004