I have the same problem with mine, after a day on the bumpy roads it seems the connections get loose in the back where the HDMI and other cable plug-in. My solution is too reach behind and push the HDMI a plugs making sure they are firmly seated, that always works in our rig. I wish there were ferrule connections like on the old PCs that had the old serial bus connection that had to be screwed in.
2014 Winni Adventurer 37F
2013 Honda CRX - Falcon II tow bar
5 Star Tune, Banks Power Pack #49380