then no...your not baned. Did you find out if the person that flashed your drive has your original firmware? If not....you can ask the question at xboxhackerBBS
"can i dl the original stock firmware for my drive and just insert the dvd key"
if you cant....then....you cant un-mod your xbox.
sucks, i know. But hold in there. Give it time the 360 will be just as hacked as the first xbox.