Have you read the thread in the link you posted? It says it gets stuck at 80%, reboot and your phone will have a grey screen, proceed to next step, which is writing the MID.
You've stated that you did the first two but now it's at a grey screen ... Do the next step like it tells you. I don't get why you keep rebooting it and questioning the grey screen when it tells you that is normal and tells you what to do next?
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