I respectfully disagree with the above comments about 225 degrees. I smoke nearly all my brisket and butts at this temp (and I live at altitude too). That said, there are several factors that could have an impact on the experience you had; some of them already mentioned above.
Are you sure your chamber thermo is accurate?
Are you sure your meat thermometer is accurate?
How many times did you open the cabinet to try various fixes? This hurts your chamber and meat temps when still that low.
Using time alone to gauge where your temp should be is a flawed mechanism. I'd have just let her cook through it.
From what you describe, when you took it out to wrap, then put it back in, you gave it an hour right? Probably just got a little impatient. What happened there was you let a bunch of heat out of your chamber twice, and then only giving it an hour isn't enough. You hit the stall, and even if you never open the smoker at that point, it's not uncommon to even notice a couple degree temperature drop during that time as the collagens break down, turn to liquid, and permeate through the meat.
Definitely try again, and remember that every piece of meat truly is different. I know people hate to hear it sometimes, but brisket is a cut that really is done when it's done.
Note: even though I disagreed with the 225 degree comments above, there is still absolutely no harm in cranking up the heat if you need to push through the stall. Or even if you just plain find that you like it better that way.