ok, thanks.I would use PicoDurangoPost to diagnose the Xbox. (https://github.com/xboxoneresearch/PicoDurangoPOST)
The southbridge board has a little NOR chip, which contains unique data. If you want to use another southbridge board, you need to transfer the original NOR data to the new southbridge board.
What happend when you use a wrong southbrige board ?






