Thanks for the walkthrough!

The area I don't understand is "9 doors hallway"

Let's assume after pressing red button the follow doors light up "4,5,7":

When standing in front of door "4", can you explain where to enter those codes using first three button? I understand button at bottom right of door should open the door.

However, I tried entering "4,5,7" starting from top and cannot seems open the door 4.

Tried entering "7,5,4" start at still starting at top and still no success.

The walkthrouh isn't specific at this point!

You're welcome.

You see the sequence of lights and they are 4 - 5 - 7.

You want to open door 4.
Stand before door 4 and use the panel that is at right side of that door 4.

Click the top button 4 times and see #4 on the frame below that button.

Click the second from top button 5 times and see #5 on the frame below that button.

Click the third from top button 7 times and see #7 on the frame below that button.

Then press the bottom button and if you did the above correctly, the door will open.