Oops
Well, don't do what I did.
The button is supposed to come out front ways. I forced it out backwards coz I couldn't see any other way. (I still can't)
I replaced the bulb with an LED and resistor - which is such a faff... I wouldn't recommend it. Next time, I'd just buy the damn Nissan bulb for $10.23 and be done with it.
Because I pushed the button out backwards, it's now disappeared back into the heater controls. Whatever was holding it in place isn't doing it's thing anymore.
I'm just going to buy an illuminated button for the dashboard now.
Wasted SOOOO much time on this.