Just got one to try for our long trip. Was starting to use it and suddenly the screen went blank. When you try to change things like RAW to JPEG, it would refuse to do it. And when you try to initialize it would fail. Argh!
I’ve never had camera firmware crash so hard. But I remembered from playing with the Canon firmware that in case of trouble, remove the battery and at least on a 5D2, it will recover.
Voila, this worked on the Sony. So if you ever really torque the firmware (it is a brand new camera after all). Take the battery out and pray!