Sortedkies now updating firmware, and the other steps were easy enough.
Samsung were very helpful and are sending me a jiffy bag to return the handset. Will take 5-10 days to return.
Fingers crossed they just replace it... on the bright side I've sure learned a **** load about flashing, odin and rooting....
Yeah, I got my first Android device in August 2012 and knew nothing. When you experiment more, it makes it less nerve-wrecking to try new things.
If you ever use an HTC device, it's basically the same process, but instead of Odin you run an RUU. (Rom Update Utility)