You can hear it running on gas if you listen closely. When you first turn on the propane, you may need to bleed the line of air, I light the stove for a minute or so. Once that's done, you can flip the switch on the fridge to gas, if it's quiet (and your battery is connected and charged), you should be able to hear the ignition clicking trying to light the fridge. Once it's lit, you can hear the propane burning if you put your ear up to the outside vent, it sounds like any other propane flame, like a really tiny jet, a low rumbling whooshing sound.
I concur with the propane alarm sounding being the result of a low charge on the battery.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!