My Phaser 7800DN recently refused to boot and is stuck on the "green screen." With the help of these boards, I was able to create an ALTBOOT USB thumb drive to update the firmware which seemed to work (got to the "remove thumb drive" message where the machine is supposed to reboot and print a status page. But it rebooted to the green screen. (I also tried to reset the GFI button with no success.) From what I've read, that leaves the hard drive and/or SD card. I have ordered a new hard drive from Xerox but the SD cards from are on back order. If I can buy a blank SD card at an office supply store, I understand it will need some type of card image from Xerox. Where do I get that? Also, can I format an SD card on a Mac or does it need a PC? Any advice on resolving the issue greatly appreciated.