Amazing read, thanks for sharing. It’s fascinating to see that it is now hobbyist-accessible to design and order a PCB that intercepts BGA connections, something that at the time was Microsoft’s sure-fire trick to disable JTAG.

This blog post got reviewed by Hackaday. https://hackaday.com/2023/08/11/using-jtag-to-dump-the-xboxs-secret-boot-rom/