DeWalt DCB404 40V Max 4Ah Lithium Ion Battery

This is a genuine DeWalt 40V Max 4Ah lithium ion battery. . Dimensions are approximately 7.5 inches by 4.5 inches by 4.5 inches (19 cm by 11.5 cm by 11.5 cm).It stopped working. I don't know what's wrong with it. If you know how to fix it then maybe I would throw the prices down a little bit.