I had the most intense experience. I almost bricked my phone. I'm sure some of you might have encountered this, but I'm really careful on installing stuff on my phone. And then it happened.
It froze! turn it off and on and it's stuck in Nokia logo. Take the battery out, memory and SIM card, still the same (this time, I'm sweating like a pig)
hard reset of *#7370# won't help me since dialer is not available.
Then it occured to me, I read this somewhere, after a few minutes of research, i found it again.
Hard reset using the hardware keys:
GREEN + RED + CAMERA button all press together
and then hit power key, wait for it to show the handshake and
you should get a prompt for pin code and/or lock code(the site says that it should go back to 12345 lock code, mine stayed the same)
That worked like a charm, it'll boot to factory default, let's just hope that you back up your stuff.
Just a friendly reminder
Hope it helps.