I have exactly the same problem and am watching this thread with great interest.

I looked at the battery contacts and can see that the contacts are a bit bent. However, while there are 5 bits of metal on the phone there are only 3 points of contact on the battery; earth, - & +. Now, the metal that is bending is only shorting out the metal that touches the same contact anyway so it shouldn't make any difference.

To try any figure out what's causing the power drain I've taken it all apart to leave just the battery, screen and board with the battery weighted down with a power supply

The result: still went flat quickly :/

Wish I could replace the recharge circuit. If I could just get hold of one that would be something.

I sent the phone away to be repaired but it came back the same without a charge. They were really busy so I can't be 100% sure they checked it. However, I gues the only thing left to do is replace the mainboard somehow, possibly by a new phone :p