10 minutes is not a long time for a firmware update, and it does say that it will reboot by itself. unfortunately there is no way of reverting back to a previous version of firmware. You could try and reset the system but that is not Guaranteed to work.
Does anyone know how to reset the firmware on this model? I updated the firmware via the net and it froze for 10 minutes after reboot so I powered it off. Now it won't boot up properly and I just get the blu background.