[geekmaster]

As I understand it, the "magic key" is wired directly to a pin on the CPU SoC chip. Each kindle uses a different key. I did try keys known to be used on other models (Vol- and Home and 5-way Down Arrow). They did not work, so it must be something else. Or the timing with when to press and release it may be different. It will take some people some to to complete these experiments (WHEN they get worked on again)...

The thing to look for is a different USB VID/PID after hard rebooting (with magic key pressed). The DX/DXG may have a different VID/PID from the other kindles in USB Downloader mode.