Looking to hang a flat screen TV over the fireplace, The firebox is a Heatilator dx36ai. Took the top cover off and to me it looked like the brick above the firebox is hollow. Started drill a pilot hole in the side and ran into a 2nd layer of brick (see picture) about 6 inches inside of the facing brick. If I push a fish tape into the pilot hole in front it is hitting the 2nd layer of brick as well. Since the Heatilator has its own chimney stack going up and I am no where near that can I just go ahead and blow through the 2nd layer of brick? What is the 2nd layer of brick for? Other options? How difficult is it to remove the Heatilator trim. Maybe the cables could be snaked down the front and then pushed through the side?