I had similar issue with mine. Found out that it can get "locked" in an alarm mode. Only way to clear was to disconnect power to the unit. On mine it was hardwired to 12v no fuse so I added pin connectors to make removing power easier vs cutting the wire.
You can try that. Mine hasn't had the issue since. It was initially set off by being in my shop and we got an old hot rod engine to finally fire up and it smoked the shop. Had the door open on the MH doing some cleaning/work on it. OOPs bad timing