Apple logo is flashing on and off after water exposure

I dropped the phone in water, subsequently it would light up with the apple logo on the screen then turn off but only when placed on an ac charger, no response with sinc cable. Replaced battery and dock connector and the same thing happens.

I took the logic board and tried it in a friends phone and it worked fine. Do i need to do something special to make the battery work or what may be the problem?

I cant use either button top or bottom and have replaced the entire dock connector and battery.