Okie dokie, here ya go, Pokie. (#12 scared me the most)
Here is the instruction how to take off the buttons:
1) unscrew 3 screws at the bottom
2) take off the cap carefully
3) unscrew the screw under the cap, from the side of a hole, using the allen key which was in the box
4) pull out the box with buttons carefully
5) unscrew 4 screws at the backside of the box
6) clean the buttons
7) assemble the box with buttons
8) insert the box with buttons to it's place
9) screw the screw which holds the button. NOTE: it should not stick out because it can cause screen damage
10) insert the cap carefully (don't push!). NOTE: check that the screen is at it's place, in other case it can be damaged
11) screw the cap with 3 screws carefully, don't press
12) good luck