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After I got banned, I used option 3b1, then I did the RETAIL XBOX HD TO FACTORY option. After that I flashed the new EEPROM. So this means that the HDD serial has not changed at all, only the HDD key right? So does MS ban the HDD serial? That would explain why I got banned again.....
MS dosen't ban HDserial numbers.
The information that is used to ban someone from live service is the HD Key.
The HD Key is stored in the eeprom.
Thus new eeprom = new HD Key.
In your situation I would ask did you figure out what got you banned to begin with and did you fix that issue.