Fortunately, you do not have to look far to find the spot where you can use the code that you retrieved by replaying Hanna Nowak’s memories. Stay in the side room of the tattoo parlor where you found Hanna’s body. The panel is hidden on the back of the seat, as shown in the picture. Input the code 3616 to unlock a secret room.
Start exploring the secret room by locating the switch shown in the picture, which restores electricity in the palce. Start using alternative vision modes in order to locate and scan objects around you. The clues to scan are: prosthetic eyes, voice recorder (hear the recorded message), chain saw and coding station. Besides, you can find synchrozine and two collectible pictures as well as view some notes and audio logs recorded on a computer (there are six of them to hear).
Your next main objective is to leave this secret room, as Daniel gets trapped inside. For that focus on the control panel shown in the picture above. There are several buttons on the panel – start by pressing the bottom-right one, marked in the picture, which will get the big table pushed aside.
Next, press the arrow down button – one of the four that operate the hook – which is marked in the picture 1. When the hook is down at the maximum, approach it, grab it (interaction button), and pull it toward the green grid, as seen in the picture 2. The hook must grapple the grid.
Return to the control panel and now click the arrow up button, as marked in the picture above. That will force pull the grid and unlock access into the tunnel. Jump in there and use Night Vision, as there is pretty dark down there. A linear corridor will take you to the building’s basement.