what's the temperature outside where you are? it may be near impossible to bring the smoker up to the proper temp if it's cold enough out. about all you can do is open the vents wide open, put as much lit charcoal in there as you can, or some burning wood chunks or logs will bring the temp up quickly. If you own a charcoal chimney, you can light the coals in that, then pour them into the charcoal pan.
If none of the above is working out, don't fret--the temp of the smoker may not be hot enough, but it's still penetrating the meat with smoke, so if it looks like a no-go, then take the meat out of the smoker, wrap it in foil & finish it off in a 225 deg. oven. You'll still get a well cooked brisket with a little smoke taste. Chalk it up to experience. :D If you've got other side dishes going at a different temp in the oven then i'm out of ideas :(
No matter what, though i doubt the brisket will be done in 5 hours. I would think more like 6-7 hours at 225, especially since the first hour you've had some troubles. If you rush it and cook it a much higher temp it will turn out tough.
I hope it works out for you! Let us know.
Wine in a box is better than no wine at all.