I could be wrong but... I pulled an auxiliary and cranking battery from a 2006 sprinter. The auxiliary was deep cycle(white just like yours), 100 A/h vs. CCA rating and labeled "not suitable for starting". IF you were using that battery for cranking it explains the damage but recovering that cell will be a real challenge with an ultrasonic cleaner. If you've any hope at all for recovering it you will need top off the cells with distilled water, charge normally, recheck and top off the cells as needed, and to put through an "equalition charge". You'll need a charger that's capable of constant charging at 16 volts and you'll have to closely monitor during the cycle. Select a safe, well ventilated, and ignition safe area preferably outside. Cover anything you don't want coated in sulfuric acid, most especially your eyes and the rest of your body. DO NO walk away from it DURING THE CHARGE CYCLE. It will gas profusely and of course hydrogen gas mixed with oxygen is extremely explosive, corrosive, and caustic. If that sounds like something you're willing to undertake don't let the wife in on it.