Enter the password as (PLUS), (HEART), (DIAMOND), and the rest as (TRIANGLE)
It will take you to the screen with the final four levels and you are outside of 16, but 15 and 14 are not destroyed and it wont let you enter 16, but you can do 15 from back to front.
Enter these passwords to go to the level.
(T) = Triangle
(D) = Diamond