Set the bottom cover/shell on top of the chromebook and line it up the best you can

Start in the top right corner and squeeze the chromebook together. You will hear "snapping"sounds which means that you are properly connecting the bottom cover clips to the main chromebook frame.

Continue to snap together the sides of the chromebook in a rotating fashion starting with the red arrows and moving along to the green, yellow, then orange arrows. Listen for the snapping sounds. See 3rd pic. You do not have to follow the order of colored arrows, but it seems the easiest.

Replace all 7 screws using a Phillips #0 screwdriver. See red circles in pic. Done!