dontrell stephens was paralyzed from waist down after the 2013 shooting .
shot by palm beach county sheriff 's office deputy adam lin in florida .
then-20-year-old had nothing in his hand but a cellphone during incident .
state officials ruled the shooting was justified after an investigation .
lin returned to work just four days after the south florida shooting .
114 people shot at by a palm beach county sheriff 's deputy since 2000 .