What's the secret of the boiler/technician room in the beginning village?

Do someone know what to do with this room ?

It's in the village from the beginning.

Edit: I found the solution alone, I didn't notice an hidden poster, during a perspective rotation.


Solution 1:

There is a code embedded in the posters on the wall.

Boiler room

Spoiler:

The numbered tetromino posters around the room correspond to the code's order.

E.g., above, #1 is and #5 is .

The code is:

RT A LT RT