hoe to fix a water damaged phone?

i dropped my samsung SGH-T629 phone into the sink whith the water running and took out my battery right away and dried out my phone. not knowing what to do next i put the battery back in to make sure it still worked and my phone was flashing back to my messages, contacts and other places on my phone. i turned my phone off and left it alone with the battery in. a couple hours later i charged it and it seemed to work fine but the battery only last about 1 hour at the most. now i have to charge it while i use it or it will die. if i charge it long enough it starts to overheat. is there any way to fix my phone or is it permantly damaged?