I finally was able to unfreeze my system,
simply by booting from my old knoppix cd
and re-installing my grub data-partition to
the mbr of the first internal hdisk.
first, an additional comment:
the original fail message:
GRUB loading
Welcome to GRUB!
error: no such device: 8f24…blahblah
Entering rescue mode …
grub rescue
I had previously interpreted this fail message
as coming from the grub2 of the failed preupgrade f14->f16
But now I am not at all sure;
it might have been from the legacy grub of the f14.
Does anyone know if the message shown above
is legacy grub, or grub2?
It would be good to know;
I spent gobs of time trying to dope out this mess.
Uncertainty in error messages don't help.
Detail:
it turned out to be trivial.
Actual sequence:
1) turned off the USB; hit power switch;
2) power back on, comes up with same above error message,
so those steps not necessary.
3) left USB external hdisk off.
That most likely not necessary but it made absolutely sure
my grub commands to follow couldn't refer to the USB.
4) booted again with knoppix cd
grub
root (hd1,8) <<<2d hdisk, 9th partition
setup (hd0) <<< mbr, 1st hdisk
quit
system gave usual grub response..............succeeded.
logged out, shutdown knoppix cd
removed knoppix cd.
turned USB back on;
computer power on,
booted back up to my normal grub menu,
back in f14 (of course, not the version I used for abortive preupgrade).
maybe now I can get my life back, no more waking up in middle of nite...
Jack