How do I enter the basement? I see a lot of comments talking about it, and the fact that in the gallery there's golden Fredina, springtrap, Mangle, & Lolbit, but I don't know how since my character just refuses to go down there. I assume it has something to do with a flashlight or something, and probably the puppet if I had to guess.
What is the top middle mark on the mirror and how do I unlock it?