boot the snapshot, select "switch to grub bootloader">boot resue menus>find grub menus>load grub menu
If it finds your grub menu boot the installed system, run the following as root
assuming there is only one drive and it is /dev/sda.

Alright, here's the output that you requested. It looks to me as though something is being requested or looked for by the system. For each item found there's a "Y" to signify that "YES" it's been found or it's there. Well, that's my meager no little to nothing interpretation anyway.

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The grub bootloader is looking for a /boot/grub/grub.cfg on /dev/sda2. Either the grub.cfg isn't there or there is something wrong with the grub.cfg file. syntax errors will cause a grub.cfg to not display.

Hmmm, but that is actually the correct location. There's nothing else on the disk. Due to partitioning the disk is recognized as SDA. The disk has two partitions, one tiny one for swap and the larger partition for the data. That Ext4 data partition is recognized as SDA2.

I've installed MX Linux dozens of times and the installer always recognized the availability for grub, and defaults to them. So far I've only encountered problems three times, this here being one of those times. Aside from those incidents the defaults have always worked for me.

When I boot into the live session, followed by using mx boot repair tool, that tool also recognizes the sda disk and defaults the grub location to sda2. If that's incorrect, where else would I install grub? This particular laptop has a second hard disk as opposed to a dvd / rw optical drive. Is it possible that the problem has something to do with that? That second drive was formatted as NTFS though, so I can't imagine that that would confuse the mx snapshot installer? Perhaps I should try to just remove the second hard disk and try the installation again from scratch?

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This is most likley the problem. At the grub prompt If you get a grub menu and it boots rerun grub-install. If you get a file does not exist message the change it to
if it is some other error message post it here.

Bummer, tried both commands and only got an empty screen with >Grub flashing at the top.
I then powered off the system and removed the second hard disk, followed by powering on again.
Tried both commands once more with identical results ... flashing >Grub at top of the screen.

When I type ... boot ... I receive an error message that there's no kernel.

When I type exit ... I receive a selection of devices on the screen which could be bootable. I say could be bootable because each possible device has a descriptive word to show what it is, enabled or not, etc. The 500 GB drive shows up as the first bootable device on the screen (it's not a bios setup screen, just a black screen). However, that first 500 GB drive also shows up as not having a bootable Operating System present. I don't have any time for this right now, but later on today I'm going to reinstall the usb snapshot, this time without the second drive being present.
Will report back on how that went.

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Wow, that's just totally insane. I left the second hard disk totally out of the laptop ... it's an old Lenovo T400 Thinkpad. Old, but definitely not too old for MX Linux. This time around I allowed the snapshot installer to take over the entire hard disk, to do whatever the installer required automatically. Went through the process of formatting the drive and all steps completed perfectly as before, no errors anywhere. And same as before, once the system was rebooted I was back to the >Grub on the black screen. There was some other explanetory text as well, but nothing that had anything to do with the grub boot menu. The earlier installation had the same text, it's just some generic advisary stuff.

Utilizing the above (earlier posts) commands made no difference and when I typed exit at the prompt, once again the hard disk showed up as hd0 in the devices that were listed on the screen. And yes, once again the disk is being displayed on the screen as a device with no valid Operating System on it.
This is absolutey nuts.

Now, just to make sure that it's not the disk after all, I'm going to use the boot repair disk to see if that will work. Will report back when I'm done.

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Back again ...
Well, either it has something to do with the disk, or with the Lenovo T400 mainboard ... ???
The live boot repair stick did exactly what it was supposed to do. It recognized the kernel & memtest settings, completed, and prompted the removal of the öive usb stick in order to complete a reboot. This time I got 2 error beeps, followed by the screen display of the menu that lists all available, potentially bootable devices. And as before, the hd0 hard disk showed up as not bootable due to a missing operating system.

The boot repair scanned the system and found everything that it needed. It went through all of the steps and promps that I expected to receive, completed without a hitch. I can also access the system data from the live usb snapshot, so I can see that everything is there. This definitely has me stumped. Tomorrow I'll try another hard disk.

Check your bios settings, I suspect something needs to be changed to allow booting linux. This wouldn’t happen to be a uefi system?
Maybe the boot flag needs to be set on the root partition.

Thanks, but it has nothing to do with the bios settings. I've been working with computers for almost 30 years and the T400 only has legacy settings anyway.

Here's something that's really interesting. Instead of using the snapshot, today I went to the system where I was trying to install the snapshot and instead deleted the disk, assigned a new partition table, then reformatted the drive. Got my prior usb snapshot (not the one that I've been having problems with) and installed that one. As expected, zero problems and zero errors. Booting up works just fine, restart etc. all working as they should.
Replaced the background image, tinkered a little more, then another restart ... no problem.

I then went head and installed the latest 4,19 kernel. Towards the beginning of the installation process some of the text read along the lines that something couldn't be found, will attempt to continue by utilizing blah blah blah at which point I could no longer follow as the kernel installation kept on running up the screen. Anyway, the process continued for quite a while, completed successfully, and then automatically shut the window. I watched it the entire time.

Another restart ...
Beep beep ... device not able to boot, hit esc.
Message there listed all potentially bootable devices and hdd0 showed up as having errors.
That's it, just a single short line by hdd0. Errors found.

I then powered off the laptop completely. But when I powered on the next time, everything was fine again. Cold starts appear to work, reboots do not. Could be the latest kernel causing a glitch? Don't know, don't have time to finish following it up anymore today. I'll be back tomorrow, to report on changes once I switch back to kernel 4,15 instead.
Have a great Saturday, and stay healthy!

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Hard drive shot?
In other words, that sounds like hardware fatigue.

All in all I have to say your posts contain a lot of narrative & paraphrasing & interpretation, but little actual technical data that we could work with. It is difficult to keep up with the actual problem among all that.

It's not hardware fatigue. The disks are fairly new, name brand, and get tested before I use them. In 29 years, dealing with literally hundreds of desktop and laptop computers, I have literally only seen about half a dozen hard disks (two of them scsi drives) go bad. It's a far more rare occurence than people believe. One of them went bad instantly after my friends's kids threw a football ... right at the pc.

I apologize for the long-windedness. Writing comes naturally to me. But in all fairness, I think that I've described issues as detailed as possible as well as the steps that got me there ... I provided results to requests made of me ... I provided a copy of the grub.cfg as well as the other grub file, so I really have no idea why you're griping about my output? I'm not a Linux Guru and I'm certainly not a Terminal Guru, so I can only provide all the details possible which more often than not don't involve the terminal. Just about any 10+ year old 64bit laptop shouldn't require any additional details for grub boot issues. Hard disk & Operating System installation should be sufficient (methinks).

I believe the problem is finally solved ....

I'll have to play around a couple of more days to be certain, but right now, after about 5 reboots without problems, I believe the problem has been solved. In recent weeks I ran into some problems with another considerably newer Lenovo laptop. No matter what I tried, pretty much the same thing happened. Grub refused to boot into the system. After tons and tons of reading throughout various forums and posts which were pretty much identical to what I was experiencing, one of the suggestions was to insert the boot flag on the partition to be booted. After I did that, that other laptop worked just as expected. Well, earlier today I tried the same thing with the current "problem laptop" and wouldn't you know it, now that laptop also boots up just fine, both from a cold start as well as from a reboot.
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EDIT: I was actually referring to another Grub post with the grub files posted. Sorry ...
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I had added that suggestion to my post 24, but you may have read it before I edited it. I have a bad habit of editing a post with additional information a while after the initial post, instead of making a new post.
Anyways congrats on solving it.

Thanks.

Well, the problem is about 99% solved and I don't think that I'll get that final 1% resolved on this particular Lenovo T400.

The reboots works about 3 out of 4 attempts. If I power off completely and then power on again, that works each and every time. I've done that about 12 times so far, always spaced out anywhere from 1 - 2 hours. First I'll try the reboot, then I'll resort to power off / power on when the reboot doesn't work. Once I was otherwise satisfied with everything else, I went ahead and created another new snapshot from the T400 which doesn't like to reboot consistently. Then I installed that snapshot into an older Windows 8 Asus and that worked flawlessly. No problems with reboots or shut-downs. I have one more item that I'm going to check on the T400 and will report back one final time tomorrow.

According to post #7 in this thread, and anticapitalista's answer in this thread ...
https://www.linuxquestions.org/quest...198/page3.html
... those are really the best answers, if you prefer not to use the boot disk.

What I didn't understand with my limited Boot / Grub knowledge at the time, was that the editing had to occur on the installed system after booting up with a live stick again. Once you're running the live stick again, simply locate the system/boot/grub.cfg of the installed system which wasn't booting up correctly and edit them as root user.

If you see a reference to some kind of 10proxy, go ahead and remove that as well. Make sure that there are no spaces between the lines, double end tags, etc. In other words, be very careful. Also, if you do have the 10proxy inclusion, then you'll want to go to system/etc/grub_d and delete just that one file, the one that has 10proxy in it. All of that as root user (right click on the appropriate folder within Thunar, then select "Open as Root" for editing.
Immediately after you're done, use the terminal to run: sudo grub-update
Then reboot.