most likely, if something is getting hot enough to shrink the wrap any more, it's the cell... and the shrink wrap will melt apart and fall off. don't ask me how i know....
that's what happened to mine. you have a bad cell, my friend. go ahead and charge it...but keep a close eye on the temps. do you have a temp gun? keep monitoring it... but i bet within about 5-10 minutes on the charger you'll be able to tell that one is getting much hotter than the rest. if that's the case, pull it off the charger.
did you try contacting cheapbatterpacks to see if they'll fix it for you?
Either the cells are out of balance enough to cause that one to reverse and/or overcharge and get hot first. OR that cell has reduced capacity and/or high IR.
IF it is a weak/bad cell then it can't really be fixed. It would need replaced of course.