Master Key Trophy
Solve all the combination key puzzles.You will get this trophy once you solve the 4 combination key puzzles in the game. To do this, you must first find the Incomplete Key inside the cell in which Anna is imprisoned by using the Acid in the lock during your encounter with her in the Experiment Room of the past and returning to this same place in the present after doing so. The second necessary item is the Metal Dial, which is found in the open bathroom area of the Basement (this is the place near where you find the electrocuted water).
Once you have both items, combine them and proceed to solve the four door puzzles (Check out the Additional Resources Suplementary Guide for the solutions of the puzzles within the game).