Mine is fine, FWIW. It's Three branded and still running the same firmware it updated to in October.
Clutching at straws - have you tried taking the SIM out and *then* resetting it?
Also, are you using the reset button or can you get into the web GUI enough to reset it via that, even if it has no internet? I have a feeling I struggled to reset mine using the physical button when I soft-locked it with a bad cell lock.