Ok Amigo this is the deal you got your cherry popped now it's time to learn how to tease that brisket until it is putty in your hands.
Your cooking at to low a temperature 180-200 is jerky making temps. You can start off low say 230 fro the first two hrs they ramp it up, You need to run your pit at 275-300 deg until that brisket probes tender Internal temps do not tell you when the meat is fully rendered and all the collagen has broken down this will not happen at temps below 220, your first result is proof of this.
This is how I cook mine it is proven and it works everytime
I light my pit and bring it to 300 deg and get a split preheating on the fire box
Then I go in and remove the brisket from the Cyro and rinse it under cool water and pat it dry
Trim all the hard fat, and thing out the fat cap to 1/4"
Apply my rub 50/50 Ksalt & med grind Black pepper
Put the brisket on the pit Fat Cap up Point to the fire box
Maintain 300 deg
At the 4 th hr I wrap in a layer of Butcher paper and go back on the pit Fat Cap up point to the fire box
At the 5.5 hr mark I start to test the flat for probe tender once it probes like butter I pull it and put it on a sheet pan and allow it to sit wrapped until the brisket s temp drops to 150 this can take up to 3 hrs.
Now it is time to enjoy a giggly moist tender & juicy Piece of Bovine Love