ok blurry was doing this fast one handed. these are pics from the back so either turn it around once radio is out or disconnect it and do it out the car. with the recirc i believe it can be done easy in car.
here is the back with the plugs half out for the recirc.
here my tooth pic is pointing to the tab you lift up to release (mine is already released in all these). once released it pushes towards the front of the unit opposite the tab. the tab is gently pulled up away from the switch with a flathead or small item. i think i used a butter knife first time.
this shows it sliding out it is missing the cover on the front . the cover does not need to be removed if i recall
this is a pic of the tab and the button with nothing blocking it
button removed screwdriver on tab to show a better pic again the tab is gently with a small flat head pushed up to release
hope that helps or at least gives you a idea. pm me if you need any help. the button is 20 bucks from nissan i think. or find a junk yard and get one hoping it works. i tried the radio shack bulb replacement and it didnt work luckily a i got this whole unit from a car going to the scrap[per and it worked fine. good luck lemme know if i can help.