soak it in some WD40 or other release penetrant first, give it a good spray and leave it overnight preferably. Is it an allen head or phillips? You could use a torx driver of a similar size and jam it in using the taper and it might move, worth trying that first before the destructive suggestions above
soak it in some WD40 or other release penetrant first, give it a good spray and leave it overnight preferably. Is it an allen head or phillips? You could use a torx driver of a similar size and jam it in using the taper and it might move, worth trying that first before the destructive suggestions above