[skellyo]

If you lit it up by plugging in the balancer, the balancing adapter was built wrong and it shorted or reversed polarity of at least one of the cells. This is why, to me, it's worth it to buy that brand of balancer to keep this kind of thing from happening, especially with cells as expensive as Flightpowers. If I were you, I'd see what CBP is willing to do since their adapter is what killed your pack.