BEFORE YOU START!!!!
Make sure you remove your hard drive or memory card out of the xbox 360 and that is it!

Instructions:
1. Turn on the xbox 360.
2. When you get to the home screen there will be no profiles found. That's because you removed your hard drive/memory card which contained all your profiles. Easy to understand =).
3. Now go to system settings.
4. Go to Network Settings.
5. Click Test Xbox Live Connection
6. Start connection and wait for it to finish.
7. When it is done you should get a message saying to update your system. Here is another important thing you need to do DO NOT UPDATE!!!!! I REPEAT DO NOT UPDATE YOUR SYSTEM!! Just click No, don't update.
8. You should get a test connection failed message. Just click cancel.
9. After that click Y and you should get a list of numbers or codes.
Check your code under the letter Z
It should say Z: "whatever the code is"
Here are the codes to determine if your console has been banned.
Z: 8015 - 1002 means you have not been flagged yet. But still be cautious when playing online.
If it shows something other than that like
Z: 8015 - 190D, that means that you console has been flagged or banned. Sorry guys.
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I hope this can clear a lot of answers whether you have been flagged or not.

Here are some more status codes


No Ethernet (Banned and Not Banned):
w: 0000-0000
X: 8000-0011
Y: 0000-0000
Z: 0000-0000


Not Banned \ NTSC (4552) | Ethernet, IP assigned (router dhcp), dns failed (modem off):
w: 0000-000B
X: 0000-F001
Y: 0000-0000
Z: 8015-1904
Not Banned \ PAL (4552) | Wireless, update cancled, never been modded
w: 0000-0021
X: 0000-F001
Y: 20A8-4840
Z: 8015-1007
Not Banned \ NTSC (4552) | Ethernet, update cancled
w: 0000-000B
X: 0000-F001
Y: 20A8-48E0
Z: 8015-1007
Not Banned \ NTSC | Ethernet
w: 0000-000B
X: 0000-F001
Y: 20A8-4840 ..also Y: 20A8-48E1
Z: 0000-0000
Not Banned \ NTSC | Ethernet
w: 0000-0021
X: 0000-F001
Y: 20A8-4840
Z: 0000-0000
Not Banned \ NTSC | Wireless, marketplace does not load
w: 0000-0021
X: 0000-000D
Y: 20A8-4800
Z: 0000-0000
Banned \ ? (4552) | Ethernet:
w: 0000-0021
X: 0000-F001
Y: 00A8-6820
Z: 8015-190D
Banned \ NTSC & PAL | Ethernet:
w: 0000-000B
X: 0000-F001
Y: 00A8-6820
Z: 8015-190D
Banned \ ? | Wireless:
w: 0000-0021
X: 0000-F001
Y: 00A8-6840
Z: 8015-190D