Point of red gramophone and 2369 code ?

[KafarPL]

Both of these lead to a dead ends with nothing there. The red gramophone whithers the plants so you can open the door but the only thing there is a mannequin in a room with a chair and a box or two. The 2369 button code activates the moving platform but there is nothing on the other end than mannequin and an empty closet

It seems that I have to turn off the giant magnet to proceed but I cant get up to the roof given how the ladder is locked with a gate and the wrench to unlock it is right behind that gate

[AtomicFinjaMaster]

The Mannequins and slices of cake together are able to grant you the gun when placed in the birthday room, you have to stop the train car near the ladder so that you can use the nearby pipe to jump onto the train to parkour to the roof.