2002 galant es radio removal

ive been trying to take out the radio in my 02 to put an aftermarket deck in. i got the plastic trim panel off, but there is a screw way in the back that only has 2 indents in it, not a phillips or flat head. is there a special tool to take these out, or is it just a cover? any help would be appreciated.

take off the trim panel,remove the heater control panel screws and behind the heater control way in theres i believe a 10 mm bolt on one side,but you have to move the heater control panel to see the bolt,you will have to re-use the two side pieces from the factory radio to mount the new deck,BTW most aftermarket stereo trim panels dont fit around the face plate with the dash panel re-installed depending on the stereo