Swelling Li-Po battery. What is the reason?

Question

Rechargeable batteries

The battery lay for about six months without use, during which time it was very swollen. Voltage - 4.08 on both banks. In what there can be a reason and whether it is possible now to "cure" it?
Marking: 2200 mAh, 7.4v, 25c out / 5c in, last charged with a current of about 300mA in an auto-balancing charger.

Answer 1

It is very easy to cure - throw it away and buy a new one.