Plunger Lock I Have A Wall Safe With A Combination Of Four Numbers. What Procedure Do I Use To Lock & Unlock The Safe?

I have a wall safe with a combination of four numbers. What procedure do I use to lock & unlock the safe? - plunger lock

It gave me security and combination. The door opened and the piston is at the door does not close. The safe sat around the last place and the owners do not remember running order. The castle itself is a sergeant.