With all electric/battery machines you have to start with the batteries, make sure they are watered and fully charged. And " I plugged it in until it was charged" is not what I mean. I mean once the charger has completed it's cycle use a volt meter to make sure the batteries have proper voltage. A good 6V GC battery will read nominal 6.3 volts. If you're reading less than 6 volt, 5.8 or less, you need to test the battery cells with a hydrometer to see if you have a weak or dead cell. Once you verify the batteries are good, make sure the terminal connections are sound. Once you have done this, if it still doesn't operate proper, then you can chase the other gremlins, but you have to start with the batteries.