Its look like a bricked machine.
Try contacting Xerox Support ASP line to get help on this issue.
We have a C8070 that will not take FW. We've tried altboot, forced altboot, special altboot file, and update through web portal. It looks like it's going to take i see the USB light up and start flashing then it boots to the normal screen, when you it try through the web it just comes up with error detected. We tried a HDD and SD card with no change. Thanks for all the support on this