My iPhone fell in water!

Hello, my phone fell to the water, it has been 9 months then today when I turn it on, it turns on and off soon ... what should I do to get it working again? change the batteries? thank you for your invaluable help ... it's a 3gs and now it stays on only connected when I unplug it turns off after a few minutes other very important problem it recognizes no chip and I have no network .. ??? what??? thank you