Yoad, the order is:
The first button is behind the filing cabinet in the building directly across from the stairs.
The second one is in the room on the left from the top of the stairs, it is behind a painting
The third one is in the room behind the dresser, it is on the ceiling
The Fourth Button is in the building with the red roof. Inside the little bar area, on the side of the bottom right corner of the dresser.
The fith Button is on the front of the buiilding next to the truck filled with crates
And the last Button is in the part of the garage with the truck, it is behind the bags of cement

Honestly I don't even remember I'm sorry. We were able to find it from googling it and looking through the threads but I don't remember what the combo was.

what was the ordwer

i think in zombie survival there is a boom stick inside.
it's the strongest weapon in the game.