Resposta para "Replaced iPhone battery but it won't charge?"The fact the old battery charges, implies there is something wrong with the new one. I'd try and get the seller to refund/replace it.
Resposta para "I did the Replacement, now it dies immediately if off the charger"Shorting a battery can cause irreversible damage to the cells. Also check for a voltage directly from the battery pack, if there isn't one then it could have become so discharged that the safety circuit has cut in. A short manual charge of the cell itself might revive it. Working with batteries can be dangerous, be extremely cautious!