hi, thanks!
i got the gray piece out, then the 3rd recessed screw, then the 3 little corner screws. total screws: 6 (3 big, 3 little).
trouble is, i can't slide the side plates towards the end where the gray piece used to be to unlock them. yes, i see one must slide before the other, but i can't slide the first. what kind of devilish trick is this?!