Problems while flying

Well, I had a good discussion about flying with my father in-law the other day. He's the one who got me hooked on the idea flying his 3-ch around, and I think I've got him hooked on getting a 4-channel. He's probably got all he needs for it, just buy an e-starter and he'll have a complete bird. I may even buy one for him if he doesn't have one by them.
On another note, the same day we talked my battery I found that my battery had died. I checked the voltage and it was under 9v, checked the cells and two were at 3.8v volts and another at 0.4v I'm guessing the charger thought it was 2 cells, charged it to 8.4v, and the other dead one backed off a bit after charging. Bah. I called Thunder Power and they said to send it in with a note describing what happened and all that. I'll let you know what happens later this week or next when I get it back. I've also been reading on doing my own batteries as a 3S lipo would be $35 max as opposed to 50 and would hold more amps. We'll see about that though, for right now I just want mine back.