Lubuntu 18.04.4 QA-test install; post-install it failed to boot - grub rescue

Lubuntu 18.04.4 QA-install (i386)

hp dx6120mt (mini-tower, pentium 4 dual core, 3gb, winfast clone of nvidia 7600gt)

Two prior installs on this box failed - filed under https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1861777 (not a blocker bug in my opinion)

In hopes of getting a 'clean' PASS result in iso.qa.ubuntu.com, I disabled two of my drives so the only drive offered was SDA achieving what I wanted. It worked during install; install looked perfect (as expected)

Alas on reboot I'm only getting

"error:: no-such-device : 5a..."
and
"grub rescue>"

Result Expected: Grub & clean boot post-install.

Note: I hate this machine's BIOSl have checked looking for any errors; but it's different to all other boxes I now use.

Note also as I only noticed the problem on reboot, I'm filing this on a subsequent boot of the 'live' installer (Start Lubuntu option). If more is required; let me know.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.14
ProcVersionSignature: Ubuntu 5.3.0-28.30~18.04.1-generic 5.3.13
Uname: Linux 5.3.0-28-generic i686
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: i386
CasperVersion: 1.394.3
CurrentDesktop: LXDE
Date: Tue Feb 4 09:58:29 2020
InstallCmdLine: file=/cdrom/preseed/lubuntu.seed boot=casper initrd=/casper/initrd quiet splash ---
LiveMediaBuild: Lubuntu 18.04.4 LTS "Bionic Beaver" - Release i386 (20200203)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)