Shut off the propane at the bottle. Disconnect one of the incoming fittings under the trailer, or at an appliance (water heater and fridge connection should be accessible from outside, where you have ventilation). Have someone slowly open bottle, and see if any propane comes out.
I had a regulator Ona previous unit go bad on the third trip out, so age may not be a factor...
Be Safe, and Everyone Goes a Home,
2014 RAM Laramie 2500 w/6.7L Cummins Diesel and Automated Safety Hitch
2016 377RLBH Jayco North Point
300W of Suntech Solar w/Rogue MPPT Controller & Xantrex 2000W PSW Inverter