I by no means have nailed a brisket but I can tell you I have had the best success fat side down . I have a chargriller with side fire box. I think I did my best brisket this past weekend. Was not store bought, brother-inlaw gave me some meat he said he would not cook and was needingt freezer space for he was ready to butcher again. Long story short fat side down about 8 hrs between 225 and 250 bout 10 lb. brisket just rotated it every couple hrs and sprayed with apple juice.
Be good or be good at it!!