...when you insert the batt into the tube, does it stick up 4-5-6mm out of the tube...if not, strech the spring until it does and give it another try...some of the E-Powers had weak/short batt springs...make sure the threads are clean as well since batt>spring>tube>threads>switch body>carto is the current path for the - side of the batt...
madjack
madjack