Button Save Glitch
Button Save Glitch - A trick which can be made only in Portal 2 SinglePlayer and Single TestChambers. This bug works only with a cube or a ball (or any prop which can activate a button)
Take the cube, and, holding it, put it on the button you want to push. Then, after quickly removing the cube from the button, save the game and boot it back up again. The button remains in the activated state until the button trigger is activated again.