I believe that button (rear blind) is an instantaneous "closed while pressed" type.
I'm thinking of using that blank space for an accessory button myself and though the logo is quite appropriate I "think" I may need a "push-on, push-off" latching type, just for a simple (signalling) circuit carrying a very low current.

Are any of the other normal PF buttons better for that function and can you swap the tops over between them? I don't even need any lighting in it.

I've got a rear blind button on its way to me (from A8parts of course) but may need to upgrade the mechanism, depending on the results of further testing - the button with the equipment is a "latching" one but of a hugely inappropriate design, though initial tests do suggest it doesn't really need to latch.

Swapping the button seems to be trivially easy, just a couple of small lugs to be pressed in to unlatch.

Funny thing is, the switch blanking plate has all the lugs on the back to connect to a wiring socket. :Confused:

BTW, instead of trying to attach separate wires to the back of your button you can get the female connector 'backplate' for your button from Audi or from A8parts. I had an old loom from FL car and I found out that backplate connector from seat heating buttons will work with my 'garage open/close button' too.