It sounds like the battery is either bad or came disconnected or possibly another cable between where the USB port is and the battery is loose. Check all cables and clips and make sure everything is seated correctly. Also take note of the shape of the battery. If it looks puffy and bloated it is going bad or is bad and is unsafe. If you smell anything funny coming from the battery it is Li-Ion gasses and another sign you need a new battery.
Good luck.