I just bought a Cushman Commander recently. I drove it around yesterday but noticed when starting it, there was a sort of humming when it's trying to start sound rather than the lug-lug-lug sound as it typically emits when starting. After sitting for a couple of hours, it only makes that humming sound and won't turn over at all. I though it might have been a low battery, but tried jumping it and same result. Any thoughts?