Comment 14 for bug 1687729

Jeff, the efibootmgr output indicates that Boot0008 is first in the boot order. That's a PXE-boot entry, as are the next three in the BootOrder list, so unless PXE-booting is failing for some reason, the Boot0010 entry for Ubuntu's grubx64.efi should not come into play. You can test this by deleting the Boot0010 entry:

sudo efibootmgr -b 0010 -B

This should not affect booting if the system is PXE-booting, but if it's failing because of a direct boot of GRUB, this will cause the system to try the additional boot entries, which include additional PXE-boot entries, the USB drive, and the CD drive. If all of those fail it will probably launch the firmware setup utility, or maybe an EFI shell.