puffed isn't always an indicator of broken. Slightly puffed is a normal operating condition of a lipo cell.
Put it in your liposack (you got one, right? you should have) and charge it in a well ventillated area.
Few possibilities:
1. It bursts... the liposack and good ventilation protect your house from burning down... get a new battery.
2. It doesn't burst, but gets puffier... the lipo is near it's end of life, and you should have listened to warnings about socom gear batteries.
3. It is over discharged, and your smart balance charger (You got a nice charger, right? That's pretty important) won't charge it, or the battery's over-discharge protection circuit activates and has permanently disabled the battery. Alternatively, you may have a battery without this protection and a low-end dumb lipo charger (yes, they make them, even with balance capabilities), and it explodes... refer to possibility 1.
4. It's fine and you go on with life.