I have a 2016 Keystone Sprinter 5th wheel. None of the wiring or relay boards look like your photos. The panels I do have are labeled rather ambiguously. I have dug into everyplace I can think of hoping for a fuse or a loose ground. No luck. I do think the issue may be similar to what you've described. I am not sure which ground to re-route as I am not sure what wiring is related to the manual switches. The switch panel itself has nothing behind it as all the wiring terminates directly onto the switches and then disappears into a hole. Of course with no labels.
