Hi, sorry to hear about your problem......it's frustrating for sure. In my case, I was able to get a mobile Dometic service person to come to our ranch in South Dakota and check it out. He removed the lower module cover disconnected the main cable between the upper and lower module as well as others....I think there is some 110/120v wiring as well. Cleaned connectors, checked the wires into the connector, jiggled and pushed then reassembled everything and it started to work properly.
At the same time, he contacted Dometic and talked them into sending out a new lower module. They were very reluctant but he agreed to waive his warranty visit fee if they would send out a new module and they did. W did not install the new module when it arrived since the old system was and still works. He asked me to keep the new module and install it if they problem starts again......then we will have a warranty issue with Dometic. I paid the rep. the his normal service fee for all the work he did and since he got the system working. We are now back at our home in Florida and the system has worked properly since his visit.
Your issue may be a little different since it apparently worked on gas, but not electricity. I assume that it quit working all together after the 8 hour period. If you were only on 12v and did not have 110/120v connected when it was working, you may have run the batteries low enough that the refrigerator stopped due to a low battery condition. If not you may have a module problem.
Hope this helps and good luck.
Steve & Lee
2013 Cedar Creek 36 CKTS Touring Edition
2012 F350 King Ranch, Reese Elite 18 and Air Bags