Nokia 6230 water damage?

Hi I have a nokia 6230 it was left in a field overnight and it rained the screen would not work had that replaced and worked fine. Now when my screensaver times out and the screen goes blank i push the button to get the screen back on but the screen just lights up with nothing else on it i have to remove the battery to turn it back on but it does the same again i have cleaned the boards.
Any help would be much apreciated many thanks again.