Once you set steering wheels correctly, pulling the upper pin you will discover the arrows which will provide you a hint for the next step
Pull the middle part of the box to discover the next lock.
The arrows on the upper pin are similar to the arrows on the small side buttons.
There are two symbols which will give you a key to open the lock.
The endings of the small side buttons are similar to the (W) and (E) forms on the box.
The two keys from the upper part of the box serving as the keys for this lock.
(W) and (E) are representing West and East.
Return the four walls from the lower part of the box to the initial state (close the window) to open the key holes.
Pull the upper pin Push the W(est) pin to the left (west) Push the E(est) pin to the right (east) Pull the key Follow the same logic on another side and pull the second key.
Insert the keys and remove the cover of the secret space.
Pull the upper part of the box – the box is split into two parts
Look closely to the card from both sides – they are connected.