Why doesn't my battery charge?

Hi,

I'm currently trying to fix my macbook pro after spilling some water on it. Everything seems to be working apart from battery charging. I can run my macbook with the battery as only power supply, and I can connect a charger, but the charger will only work as a power supply, and not a charger. The LED on the magsafe won't turn orange, and it wont charge the battery. Sometimes when the computer is turned off and I connect my charger, the computer turns on. Any ideas?

My battery is newly bought, and should be working, so I doubt the fault lies there.