Year model? does charger come on when attached t cart? When did cart last run? Does the solenoid click when the pedal is pressed?
Unless you have a trickle charger , a charger left plugged in, will not cycle and keep batteries charged. Do you have voltmeter to test battery pack voltage?
What happens when you plug in the charger. I assume you have unplugged it.
Unplug the charger , wait a few seconds, then plug it back in.