Do any of the lights come on, radio, etc? If not, check your master shut off or battery isolator switch - if you have one. Our Palazzo has a storage switch by the door that cuts power, we also have an isolated switch in the battery compartment. Check to see if there is any voltage coming off the switch. Turn it on and off a couple of times, perhaps corrosion in it? Just my thoughts of what I've seen. If there is no power on the D.C. Side and the batteries show voltage a cutout or fuse link is tripped or blown. Is you said, there is nothing when unplugged, there is a transfer issue I think.
Chuck and Mary Ann
FMCA, Good Sam Life Member and Thor MC member
Enjoy the journey, one day at a time!