Ah so the button is broken?
The button doesn't flex, it's the switch housing that opens out slightly to slide the switch out.
Is the actual housing broken, or just the clips stopping the switch from sliding out when clipped? If so it will possibly go back together and still work, as the switch cant move back when assembled.
I'll get mine apart in a bit and see if I ca nsee what you mean. Unless you've got any pictures of it?