Was your exhaust vent open all summer? May have an obstruction in it, like a mud dauppers nest...happened to me once...fan fires up, tried to ignite and just went back out...but it DID try to ignite...had to pull the exhaust pipe out and was able to break loose the nest...presto, worked great afterward...I cover it with white duct tape in summer months.....
......or as other posted, might be an issue on your circuit board.
hope you get it fixed soon and to your liking.
Jim & Kathy, (Boxers, Buddy & Sheba)
2016 Ram 3500 DRW Longhorn 4X4/CC/LB/Aisin/4.10/rear air assist ...Pearl White.
2016 DRV MS 36RSSB3/ W&D/ slide toppers/ DTV satellite/ 5.5K Onan propane gen.
B&W RVK3600 Hitch
Fulltiming in WV & TX
USAF 71-75 Viet Nam Vet