Melnickj has the right idea to flush the electronics with distilled water before powering up again. Pure water doesn't conduct electricity, it's the impurities in water that do. So as the lake water dries out it is a lottery as to whether or not it deposits some particles of conductive miners in the wrong place. Throughly rinse in distilled water and then throughly dry. When you think you have blown it dry it still won't be so leave it some warm and dry for a few days to be sure. You could be lucky, but it could already have been fried. Persnally I have had good results using this method.
John