We purchased this electric pallet jack with dried up batteries. Just installed all four brand new batteries and have let it charge. I think. When I plugged it in to charge the green light at the top came on. I checked a while later and it was off. I assume that means it is fully charged. So I unplugged the charger, disconnected the jack's plug from the battery and plugged it into the unit, clicked on the power button and nothing happened. I hit the green button on the controls and a red light came on and then off. Am I doing something wrong or is there maybe something wrong with the jack?