This is extremely easy to overlook. This screw is a different color (silver versus black) but when you’re in the swing of removing all the screws it’s tempting to just remove ALL the screws. I goofed, had the buttons fall out, could only find 3 of the springs. Put two back in the volume rocker and only one in the power button since it’s smaller, seems like it wouldn’t need two as much. Everything still works, maybe just slightly less tactile than before. Even without the the springs, there’s still some mechanical return to the buttons, so if you do lose them don’t despair.