In all the talk of graphical downgrades no one seems much preoccupied with 'why?'. Why build something and then proceed to tear it down, piece by piece, in the hope that ever more diminished expectations about the final product won't be severe enough to...
Press the switch at Bottom Right and turn off the light. You will see the following shapes during dark:
Triangle Shape at Top Left and Diamond Shape at Bottom Right.
Slide the Left door to Left and then slide the Right door to Right. You will see another 2 shapes there:
Square Shape at Top Right and Circle Shape at Bottom Left.
Now, slide the Top door to Top and slide the Bottom door to Bottom.
Follow the shapes that you've remembered just now. You can Slide back the door if you cannot remember but once the shape correct, the door will be opened.