Read this
THREAD
BetterBoy's post #137 should solve your problem. I've added some info below his post to fill in some gaps.
EDIT: I'm guessing you can't access your device serial from the device settings?
Settings -> About Device -> Device Model -> Serial number
Hopefully you kept the original box which will have a sticker with the serial on the side. (Bottom underside on mine)
If you try with a brand new microsd card you can keep the original in its current state which you can put back anytime, so seems worth a try.
You will need to open your device which I presume will void the warranty. You obviously continue with this processes at your own risk!