Ok, seeing the pics jogs my memory. You need to remove the front panel to get to the screws so take off the back of the amp. There are screws underneath the top and then underneath the amp (two each though there could be 4 on the bottom, two to fix the bottom plate in place). The faceplate should then be loose and you can pull it off. Be careful with the power switch though and the led since they are fixed on the inside.
If you can see light shining through the holes then the screws are probably inside the amp or in the box it arrived in. They are hex or torx so bear that in mind.
Nate could be right here.