Yep and thats a symptom of a much deeper problem i'm afraid. The battery causes electolytic corrosion bewteen the various components which starts the second that water gets in there. Once its started it'll get worse and worse. We used to service radios that had water damage but we wouldn't give any kind of warranty on the repair becasue its 99% certain that the unit would fail again within a few weeks.
Seriously, give up now and buy another one. Your phone is scrap.