Dometic refirgerator not working on electric

You have done some good elemination/investigation of the problem.  But the Dometic 8501 has a serviceable life of 5 to 7 years. There are a couple of things that could be causing the problem you are having.  There are several electrical components if not working correctly that would cause your problem. Such as the "motherboard" or the 110v electrical elements them selves come to mind.  It depends on just how much you want to invest in your fridge. Hope this helps you and feel free to private messsage me if you want. Jay