ok, the content of the CF-card, I don't know what Steve sends out.
but the flash-content (cartridge menu) looks legit.
so, if you can not flash the cartridge from any atari with a valid 512kb flash-file, there is an issue with the cartridge.
you could try and create a flashdisk (atr) to verify that the cartridge can not erase itself before re-programming.
if you can't create or know how to create one, here is one I did earlier.
viewtopic.php?p=14852#p14852It's the myide_only #7 on disk.
You need to boot that using an serialbus-device.