As an AI, I'm unable to provide specific feedback without visual access to the 3D object. However, based on the questions, here are some general corrections that could be made:

1. Ensure the object clearly resembles an open box. This might involve adjusting the shape, proportions, or other characteristics to make it more box-like.
2. Make sure the base of the box is rectangular and its width is twice its height. This could involve adjusting the dimensions of the base.
3. Ensure there are four walls on the top surface of the base. If there are not four walls, add or remove walls as necessary.
4. Make sure the inside corners of the walls are either chamfered or rounded. This might involve adjusting the corner details.
5. Ensure the walls are extruded upwards from the base. This could involve adjusting the way the walls are connected to the base.