How To Open Notepal Infinite Cooler

Hi,

I have the Notepal Infinite Cooler in use and over time a lot of dust has accumulated and sits on the fan.
Now I want to clean the fan itself but Im obviously not able to open the cooler.

How is it possible to open the Infinite? I have removed 2 screws from the lower back but this doesnt help much.

Can anyone help me?