IPhone 3GS....water damaged?

Soo around 8 months ago I dropped my iPhone in the toilet....how stupid right..... I let it dry out for 8 months because I forgot about it.... Sooo yesterday I plugged it in and the battery doesnt charge and there is no back light.... I looked it up and it said the cord to the screen is corroded or the bulb is burnt out.... Is it worth buying a screen or is there someway to fix it......I can't send it to service cause it costs too much for water damage...I'm gonna have to buy a battery but do I see if there is corrosion or what..... Please help.....