Enter the "first floor of Fengshen Palace" and there will be a storage point in front. After archiving, go left, open the mechanism with a big treasure chest (blue), then go right, turn on the second switch (yellow), go north along the road, turn on the third switch (red), and an animation will show that the wall rises. When you enter the area behind the wall, the wall will fall down again and there will be stairs behind the platform.