I know this is an old subject, but I have come across this same issue. I have two of these models. I have compared and swapped out parts to troubleshoot. This is not a battery issue but the circuit board. The battery indicator says 0 but when I swapped out the circuit boards, the indicator showed 100 and the lift worked. There is something in the board that is not sensing the voltage of the battery and not allowing the forks to lift. Hope this helps.