A brain damage cannot make a person unenlightened... I don't think so I will tell you why.. First of all, matter vs consciousness problem doesn't matter here... During our spiritual progress, we are kind of deprogramming ourselves.. The work is like unwinding the knots, undoing certain associations and going back to the source by digging in. When we do spiritual practice, the effects of the practice can be observed in brain.. But that doesn't mean that a brain damage will take away all this..  The reason is: A brain damage is not capable of redoing those knots....  Our mind before enlightenment: A brain damage cannot do this all over again. Spiritual enlightenment is already a losing matter. It is not gaining something but losing something.. Losing the illusion and going back to the innocence of non-duality which is your true nature.. It is like peeling the layers of onion.