If the "metal object" that is spoken of in that guide comes out of the other jewelery box, then I suspected as much. But what I was asking before is what do I need to do to open the other box (the one with the round recession below the lid)? I don't remember seeing any spherical object anywhere.
Do I have to shoot the lid of the box open, or leave it in the ceiling trap room? Or do I pry it open with the knife? I just don't know
