<sigh>

OK, I enabled Developer Mode to allow use of the terminal. Device appeared to install the developer modee OK, and rebooted itself as it had said it would do - but never came back up, just got an error screen sayng:

Device is Malfunctioning
You may try reflashing the software. If you are unable to do so, or the problem persists after flashing please contact customer service

Am I stuffed? Or is there anything I can do?