It sounds to me like there is an airflow blockage between the freezer section and the fridge section. I believe that all of the cooling comes from the freezer section and the refrigerator section cools by convection from the freezer unit. Sounds like it’s not frost blocking the airflow since you turned it off for days to defrost it. Maybe the Dometic has some sort of circulating fan to move air around the box that has failed? Good luck and let us know what you find.