Have some one else put in the battery for you. Maybe it's some corrosion or other failure but determining why usually costs more than replacements.
Look in the user manual for any RESET features.
This is a "like new" video camera that was hardly ever used. It has been stored in a case in an appropriate spot in the house. It had not been used for about a year and when I took it out of the case, the battery was dead. I attempted to charge the battery but the battery would not charge. The camera comes on when plugged into AC power. I ordered a new Lithium battery and this would not work either. Why would this happen?