I just had the same happen to mine. I'm staring at the Nokia logo right now. It's been this way for 20 minutes. If I do the 3 button reset, it just starts the same cycle over again -- AT&T logo screen, and Nokia logo screen forever. Yikes!
I had the same thing happen with my Red 920. It started having sound issues and then I tried to reset it thru the menu. Cogs on the screen which I let run for a couple hours and then I tried the button reset.
Ended up having to exchange it and got a white one. Hope that is a bug they fix.. Resetting should not brick the phone.