When I need to open up for cleaning, etc. I just shut the power off to the stove (outlet on a switch, same as unplugging). And let her die for a good 20-30 minutes while I do other things. By then it's cool enough to open but still warm to the touch, get in with a stiff-bristle brush, something to sweep the fly ash loose and down into the pan. I made a long handle so i'm not actually sticking my hands over the fire, which is smoldering but still warm.
Leave the ashpan door closed and just brush the ash from the top down. Then I'll tap the stovepipe to knock the loose stuff down, do the heat exchanger, and lastly clean out around the ashpan base and sweep up around the outside. Tried the vacuum, but a brushdown works just as good in my case.
Till I do that, the glass is almost always cool enough to clean, then close her up and flip the power on. Takes longer to let her cool down than it does to do the work now that I have the routine, and the fire comes right back when done.