LMM Battery/charging problems

COWBOYTRUUUU

New member
Nov 29, 2011
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i have a 08 durmax and the battary ran down so i was jumping it off and got the leads on the wrong terminals, pos was on neg.... now it will not do anything at all, now i have put 2 new batterys in it still not a thing ,,whats the box on the pass,side mounted on the firewall? any help out there????

Thanks,
Craig