Battery discharging rapidly when turned off

I have an Ipad 1 Wi-Fi model A1219. I recently did the latest update to it and now the battery is rapidly losing charge. Over night it will lose up to 50% and over the weekend it will die completly and not even attempt to power on. Both instances this unit is powered off using the red slider bar indicated "Power Off" There is nothing added to this unit beyond the factory installation. Any ideas or suggestions would be greatly appreciated.