[additional info from OP: I want to emphasize what I didn't explicitly say in my post: I can of course hit the power button, but when powering back up I only get back to the original fail message: GRUB loading Welcome to GRUB! error: no such device: 8f24…blahblah Entering rescue mode … grub rescue > So I have no way to boot my other f14. That 8f24… is the UUID of the f14 partition on USB that I was trying to preupgrade to f16. presumably, "no such device" because that partition is sda2 on external USB, which grub2 can't see. That original f14 was overwritten by the preupgrade-- it was clear that the process had got close to final steps. But that 8f24 partition, has since been reformatted in my frantic steps trying at least to get out of this "grub rescue >" jail. -- Another peculiarity: when i boot up with an old knoppix cd and examine the system with its legacy grub grub > root (hd0, root (hd1, root (hd2, hd0 is the external USB hd1, hd2 are my two scsi internal disks. what is odd is that "grub root (hd0," can see the USB which is not my previous experience using the knoppix legacy grub on this system-- then, only the two internal disks were seen. It's as if my garbaged preupgrade to a grub2 system has somehow modified the behavior of what legacy "grub > " sees !!?? If I were to attempt to reinstall the legacy grub bootloader to MBR of first internal disk using knoppix cd: root (hd2,8) <<<9th partition on 3rd disk seen by "grub >" setup (hd1) <<< mbr of 1st internal disk (my grub data-only partition is number 9 on 2d internal disk) BUT, the mbr install was previously done using this same knoppix cd when the USB was not visible to "grub >" so then the original commands were: root (hd1,8) <<< 9th partition on 2d internal disk setup (hd0) <<< mbr of 1st internal disk As it now stands I am completely baffled. I would like to hear comments from the list before trying either of above. I don't mind so much the failure at the near end of the preupgrade; I knew I had to jump thru some hoops because or my system not being able to boot from USB, but this mess!? Jack -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org