The darkish fragment can be extracted from the wall.

Some edges of the fragment match the edges of the wall.

The crowns also have symbols on them.

Note the sliders near the crowns can move up to 3 levels. Each slider connects the symbol on the crown to the

Look through the keyhole between the torches. It’s better to do this in a well-lit place. Make sure the

When the fragment fits the wall, you will see the correct combination in the holes. Set this combination on th

Here are all positions of the fragment. Set the sliders as shown below to connect the pairs. Rotate the wheel

When you see through the keyhole, you may distinguish the shapes of runes inside. They have the same positions

The slider on the box can move, but you should unlock it first. Pay attention to the note symbol which unlocks

Note each spiked ball is connected to a gear via chain.

The same note symbol can be found on the image of the trumpet.

Set the runes on the gears as shown below. Then take out the the key.