Problem with battery replacement
Hello. I bought a replacement battery for the iPhone 3G in your store, but after replacing the iPhone says it is very hot and gets an exclamation point on the screen. I've tried to take back and neck by four times, but did not work (problem persists). iPhone does not work with this battery. Replace the old battery, and the iPhone works normally (although for a few minutes).
I have been fixing iPhones for almost a year now, and from my experience i have found 3G/S batteries to be VERY dodgy. Regardless of who you buy the battery off, for some reason there is a high percentage of faulty batteries. Whether it be the logic board's damaging them upon installation (static discharge or other electrical causes) or purely because they are made from a poor design, its all about the luck of the draw.
Make sure that when you replace the battery again next time that you are not around objects that can create static (carpet or other friction surfaces), or you can invest in an anti-static wrist strap that earths you, that will do the job too :)
Anti-Static Wrist Strap - Anti Static Wrist Strap
My advice is to send back to the iFixit team and request for a replacement. They shouldn't have any problem with that :)
Prevent static charge build-up while working on sensitive electronics — 26 available at 7.95 each.