Were you just runnig the Heater? if so did it work okay?
The fan will stay on for like 2 minutes after you turn it off to cool it down (or after it reaches the temp setting). Perhaps this sensor that tells it to run is defective?
Do a search on you tube for fixing an RV heater. I came across one last year that was very informative. Perhaps this will help or someone else can chime in with the correct answer.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor