Place the RING on the latch. Open the hatch; take the CLIMBING PICK (L).
Open the book; take the SLIDE 5/5 (M).
Go to the Hidden Niche.
Open the side projector panel and place the LIGHT BULB inside (N).
Place the 5 SLIDES on it and select the button to scroll through the 5 slides; observe the code (O).
Enter the code from the slide on the cabinet lock (P).
Take the ID CARD (Q), TILE 2/7 (R) and TRACING PAPER (S).
Go to the Square.
Use the ID CARD in the slot of the door to trigger a puzzle (T).
Move the plate across all the cells.
Select the squares in the order listed (1-10).
Go through the door.
Take the TILE 3/7 (U).
Go forward through the door on the right.
Examine the chalkboard; take the TILE 4/7 (V).
Go through the door on the rear left.