I had one of these engines and the one comment I caught from your description is that you were using a 4.8v battery. Mine required a minimum of 6 volts to a maximum of 8.4 volts. It had the module you can see in manual. Also 2 magnets not one. Something does not sound right, are your sure it is a GT2? notice where the plug screws into the head, is there a round shield around the bottom? if there is it is the older version using the 4.8 batt.