AV Switch nut too tight

Hey there, just got my AV switch from TCSS and the nut is too tight for me to get off. I tried to pry it off with a rubber band and a wrench, but no luck. I then tried to heat the nut with a lighter but I'm worried that it might damage the finish or the underlying electronics if it gets too hot. Any advice?

You definitely should not use heat on it, the insides are plastic.

Are you sure it wasn’t crossthreaded?

Unfortunately I'm not sure, I received it this way. I'm not mechanically inclined and I don't know how to identify if that is what the problem is.