Installed in a motor home is not considered a normal installation and yes they can and do deny warranty for these types of installations. You can try to play it any way you want but it can be denied.
I owned a appliance repair service and would never touch one unless it was out of the cabinet. The only way we would even consider it was if it was at a rv dealer and they had removed it from the cabinet for service. I have warned people here before that a lot of these refers has the electronics in the back of the refer some in the compressor compartment and some up on the back.
You will pay for two techs if you can find some one to do it. Most companies will not let the customer help due to the risk of injury and insurance.
I would make sure you did not put it in demo mode trying to get it to work. If in demo mode the lights can be on but wont cool.
