did you use screws through the side of the fascia to mount the stereo??
the reason i ask is that the fascia could be being pulled in too much at the sides therefore causing the button issue
i presume they work fine when not in the fascia??
the stereo i would imagine did not come with a metal cage (most of these cheaper units don't)
as for removing it from the dash in the fascia it will (or should) just push out.However the side screws in the fascia can make it very difficult to get out from the dash as the screw heads sometimes protrude past the trim