Fridge runs on gas but not electric

[JohnDar]

The large hex nut could be it. Worth a try, any writing on it? I would unscrew it a few turns and see if you get gas.

WARNING, WILL ROBINSON! That hex nut fitting may be the pressure test point plug, not the valve. Opening it with the propane on may result in a larger release of propane than you'd like.

If you look at page 8 of this Dometic manual, there is a diagram of the gas system. It shows what the on/off valve should look like.