balance

Hello, Sorry if I put this topic in the wrong section, I'm just new here. Anyways, lately I found my good old RC heli that I remembered I stopped playing with it after it hit the ceiling and fell because ever since, everytime I try to fly it, loses its balance. But now I really wanted to start...

So I've got a 6S 5000mAh Turnigy nano-tech pack. I puffed it slightly once due to over discharge (put it in the heli for a flight by accident). Lately it has been causing my charger to not complete the charge and balance (iCharger 3010b). All other packs complete fine and in expected time...