Hello, Dan Rogers.
This can happen for several reasons: malfunction of the battery itself; expiration of battery life; malfunction of the battery controller; malfunction of the power controller; faulty/unsuitable power supply; malfunctions in the power circuits. But in any case, you should contact an authorized service center as soon as possible to remove the battery and diagnose the device. Based on the diagnostic results, it will be clear exactly what the malfunction is and whether the device will need to be repaired or not. But the battery needs to be replaced, that's for sure.