I'm sorry to hear about the freeze - thank god for the data cloud with all of our books in it!
My Nook had a freeze the first day, and I googled and found a fix that has helped the one other time it froze. Customer support probably told you to do this already, so I'm guessing it didn't work, but...
You pry off the back panel to access the battery pack. Then, you get a small screwdriver and unscrew the battery pack. You take it out, leave it out for about 15 seconds, then gently reaffix it (there are little prongs that need to go back into their slots before it swings into its slot). Be sure it is firmly in place and has full contact with its battery pack, then try to turn it on. Mine came back both times the first try with this.
It's the only problem I've had with mine, which is good! It's very hard to be without it for a time - hang in there (and you can install their free computer reading app and read it on your laptop in the meantime - not nearly as fun, though 
