Fixing a Grub Foul-up

["Martin McCormick" <martin.m@suddenlink.net>]

I have goofed, I think.  There is a serca-2000-vintage Dell
Optiplex that has been working fine up to yesterday when I did
the usual apt-get update followed by the apt-get upgrade on
buster.  The update and upgrade appeared to work.

	One of the things that got visited was grub and it was
then that I was reminded that there was another drive in the
system that had a bootable image of buster on it also.  Grub
reported seeing it on /dev/sdc which is coorrect.

	This particular system has a zip drive that always shows
up as /dev/sdb so the next hard drive after /dev/sda is /dev/sdc.

	I rebooted to make sure all was well and waited and
waited . . .

	The system sits there like a bump on a log.

	I have a usb device that lets one mount IDE and SATA
drives that are outside the system so I pulled the sata drive
which is the boot drive for the now dead system and plugged it in
to the usb converter.

	the drive breezes through fsck and looks perfectly
normal.

	I looked at /boot/grub/grub.cfg which one is not supposed
to edit as grub builds it based on /etc/default/grub which one
does edit.

	If I was to mount that partition on a working system, it,
of course, will have a different device number such as /dev/sde1
instead of /dev/sda1 which it should have when booting up the
system it normally runs in.

	Is there a safe way to mount this drive, possibly using
chroot, re-run grub-config and get the drive bootable again?

	If I look at grub.cfg and /etc/default/grub, everything
looks as if it should work but it doesn't.

	I think boot problems are some of the most agrevating
issues.  They are true show stoppers.

	I've got backups but that's beside the point.  Unless I
can fix whatever happened, it's going to be quite a time waster.

Thanks for any constructive suggestions.

Martin McCormick