After looking around this site there is also the possibility that there is damage to the logic board if the battery will not charge.
Anyone replacing a battery on a iphone i would suggest to keep the old battery when replacing it until you know the new battery is fully functional.
I would also suggest being careful when pulling the logic board out. If you have a hard time pulling it out look it over for screws or wiring that should be taken off first. Once its disconnected its pretty easy to remove.