The "Iron Will" skill card from the Exodus expansion states that "If total strength in this skill check is within 4 of the difficulty, do not trigger the fail effect". The fail effect of a skill check to get out of the brig would be that the character does not get out the brig, so basically "Iron Will" would result in the character getting free. I know that "not triggering the fail effect" is not equal to "triggering the pass effect", but the rules are a bit unclear in that particular matter.

Assuming you are serious... there is no fail effect. Closest equivalent would be "nothing happens" - and if the nothing happens doesn't get triggered... I guess nothing happens. And all robots heads exploded do to logic overload.