Defective or not, once run down it's toast now. You may bring back a heavier, better quality aftermarket battery somewhat, but excess discharging causes sulfate deposits on the lead plates and it will not accept a charge. Take the opportunity to upgrade to a gel or AGM unit, or at least a better conventional battery.
Same thing happens as batteries age. You lose plate surface area, so an older one won't supply enough power, or take a charge like it did when new.
Last edited by seabreeze_97; 08-26-2008 at 11:51 PM.
Reason: Additional info.