First check if there is corrosion on the battery or actual drill receptors (if it is green) than just pour some pure lemon juice on it, wait for it to disintegrate and wipe away with as close to 99% isopropyl alcohol but not those medical pads because those contain typically only 50%-70%. If that doesn't work check the inside to see if the connection from the battery receptor to the circuit board (CB) is fully connected, CB to drill bit. Check the receptor from the drill trigger to the CB, or test if the trigger sets off the receptor at all (see if there is contact or any other way that the trigger would set it off. If none of these check the drill motor connections, replace the motor. If the motor is replaced and everything works then it's a CB problem.