Hey im a newbie to class a motor home. Im looking at a 91 bounder have few questions. The guy who has it know nothing bout it it was gave to him. He drove it home was bout it. I hit the button for the gen on the dash an nothing happens.went outside push the start button on the gen an still no cranking or anything. The 3 batteries up front under hood look new. But even on inside none of the lights Will work. He didnt have it hooked to power cause he said the inverter was making a hum sound. The rv starts right up. Only other thing is he had the alternator off to replace it but she fires right up sounds good. Is there somthing turn off reason not getting power. I tried hitting the brown buttons above the door for battery an still nothing. Any idea what i need look at or do or Whats wrong.