HVAC lights & screw size

i have uploaded 2 pictures so you guys exactly know what i am talking about
first picture is the front of Climate AC Heater Control when i press any of the 3 buttons (marked them by red arrow) the green light light inside the small window lights up. but none of the 3 symbols are illuminated does anybody know if there is a bulb there? as i have already replaced the 2 bulbs that lights up the hvac

this is the second picture, over here i am looking for screws does anybody knows what size is the screw also in the picture you can see the two bulbs behind, those two bulbs are already replaced but 3 symbols still do not light up