First, make sure the use/store switch is in "use".
Second, make sure when you push the button, you hear the "clunk" of the solenoid engaging.
Third, some models had a wiring issue from the factory, where if the battery is completely stone dead, the converter will not charge it. The quick fix for this is to connect a battery charger to the batteries for a few minutes so the converter will see voltage.
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.