On the third upgrade, my USB flash drive is no longer recognized as a boot
device. The fourth bios upgrade is a shell script run from RHEL which the
support was also added later. I tried that first but it didn't work. Didn't
get any errors, it just didn't work.
Any help would be greatly appreciated.
You might try one of the boot disks at http://bootdisk.com. They also have
info on how to create them.
Hope this helps,
CentOS mailing list