I agree with everyone urging you not to give up. I've cooked 3 flats, each one a little better than the previous (thanks to hints from everyone here)...until I finally decided (worked up the nerve is more accurate) to do a full packer. It was the best yet, and I highly recommend a full packer vs flat anytime - if you have the extra time and money that is
Now I always inject with beef stock mixture, foil at 170 with about half-cup of left over beef stock in the foil, and cook it till its probe tender. Rest it on counter for a bit (under aluminum foil tent). And I de-fat the juices from the foiled brisket and have that available for folks that want some Au Jus...like me.