Most appliances now have a security screw fitted so that you need a special tool to remove them , this is a torx driver with a hole drilled in the bottom to accept the small dimple inside the screw head

Get a thin bladed terminal screwdriver file a small nick into the centre and file it down so that it fits into the head recess.

By applying a bit of pressure they normally come out

I would replace them with normal versions or hacksaw a slot across the top and us a straight screwdriver to put them back