My two cents.
There is no convincing evidence that brain damage results in (complete) lack of free will.
Being able to make choices does not seem to be affected by brain damage. Rather what seems to be affected, is how one perceives the world and values the world.
In the same sense, we can mostly agree, that a blind person does not lack free will per se simply because the person has visual perception problems.
In this sense, one perceiving that what one has in his hands is a fruit instead of a soap, and wanting to act in order to eat it, is no failure of free will per se, but rather of perception per se.
Valueing things differently and possibly outside a social norm, still.makes makes us responsible for our choices. One may fail to perceive and thus value a (constructed) social norm. This sounds more plausible and one can be excused because of that. Since social norms, being social constructions, are based on memory of individuals instead of some natural property for their recognition, and memory is the first thing that fails in brain damage.