You will have to drill it out starting with small pilot hole, if you reverse the drill it may unscrew the bolt for you keep trying as you increase the size of the drills, but the BB will be knackered in any case.
@Helium started
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You will have to drill it out starting with small pilot hole, if you reverse the drill it may unscrew the bolt for you keep trying as you increase the size of the drills, but the BB will be knackered in any case.