Variables

could you set up the conditional using multiple conditions, set to "all of the following", and check for "yourvar" "contains" "a", "yourvar" "contains" "b,"yourvar" "contains" "c"","yourvar" "contains" "d","yourvar" "contains" "e"

and set it on a timer say every .5 seconds to get when they are all clicked

another would be to set 3 actions on each box that would 1)set a boxesClicked to +1 only if box_x_Clicked=0 2)would set box_x_Clicked=1 and 3)check if box_x_clicked=5 then show next button.