iPhone 4 won't charge and reboots constantly.

From beginning.. I was given a water damaged iphone 4 from a friend. It took a spin in the washing machine..

But!

The telephone works perfectly for about 5 minutes before it just reboots and does it constantly, and the battery refuses to charge, but it's feeling the wall loader and give the sign of "loading" but nothing happens. I've ordered a new battery so it will probably charge then. But that is not what im worried about..

The thing is, everything works for this short while, internet, calling, texting and so on. But then it just reboots, beforce it reboots I lose my coverage and then maybe 2 minutes later it reboots.

My solutions step which been made:

1) Ordered a new battery

2) Just had it to try in parts for about 1,5 day.

3) Reset phone through Itunes.

Im worried the battery change ain't going to affect the rebooting problem? What could be the solution to the rebooting problem? Can it be fixed by just changing the battery? The warranty is out, so im trying to solve it as cheap as possible.