Help Extended Battery Question or general batt issue

[xefe]

So I had the extended battery and case from seido... absolutely LOVED IT. Then yesterday Im running low on juice, so I let it power down and charge it up. After about 45minutes to an hour, Its showing FULL charge. So I turn all the radios on and the led flash light (to drain it a little) and leave it on for 5minutes for me to take a shower. I come back and phone is dead. I got a VERY VERY VERY FEINT low charge light. I left it on there for a full day and its still dead. I switched batteries and the phone works fine. Is there anyway to bring my battery from the dead or is there any warranty that seido offers that someone knows about ? bought the battery in march.