From memory of my old s300 crankset - the chainring bolts didnt have the standard slotted bit - they were allen key on both sides - like 4mm one side and 3 on the other or something. So much better than slotted ones.
I bought one of those little shimano chainwheel bolt tools . I was surprised by how small and epically shit it was. It was useless for getting them out if they are really tight and/or corroded.
I resorted to a fucking big screwdriver which did the job.
From memory of my old s300 crankset - the chainring bolts didnt have the standard slotted bit - they were allen key on both sides - like 4mm one side and 3 on the other or something. So much better than slotted ones.