The staircase light next to my flat broke down and I would like to fix it. The ceiling lamp is pictured below:
I have a problem with unscrewing the screw. The screw is of rather peculiar shape with a little bit of space on the side and a full middle, reverse to a normal screw. I attempt to show this in the picture below:
I tried to budge it from left and right with a small screw driver but it doesn't work. I would be very grateful for any advice on how to unscrew this things. If someone could kindly point me to a tool / special screwdriver that I could cheaply buy on eBay to move this thing it would be amazing :)