I have a water infected 3G iphone. It doesn´t respond to anything.

I opened it and could not see any major damage. The battery connectors were a bit corroded so i scraped them clean, still doesn´t respond.

My question is, if everything else would be ok except for a short circuited battery would it work while connected to a external power source or does the currency run through battery anyway? I´m trying to figure out if the battery is the problem or the dock or both. Does anybody know any good measuring points i could use with a multimeter to figure out where the power is going.