Ah, but that’s not what you wrote. 
I don’t know what your intention is with the cloned drive - that is, whether keeping it in case of emergencies, or not - but, if it’s intended to be repurposed, you could connect it to another computer to perform the repartitioning, and reconnect it as a new disk when done. Cheers.
Oh dear: NOT cloned! I had initially intended the extra drive to just be storage. However, after my main drive refused to boot, I installed a brand-new Manjaro installation from a brand-new ISO in order to have something working.
The disk with the identical UUID. Better?
Aside:- Incidentally, some manufacturers have been known to release batches of SSDs with the same PARTUUID in years gone by; whether this was a similar occurrence, I can’t say.
Haha, sure, but what would be better is a working main drive. 
The two drives are from two different companies, so I doubt that theory.
Earlier, I had speculated (sheer speculation, mind!) that I might have accidentally referred to the original drive while setting up the secondary one. Could that have caused it? I don’t know, it’s just speculation anyway.
Speculation is open to anything after the fact. 
Glad you’re up and running.
Regards.
I’m not up and running. I’m writing straight from the live CD at the moment.
I just realized that creating the secondary drive could not have been involved in the “cloning” because I completely wiped that drive again after the problem occurred in order to install Manjaro on it. I mean, those UUID’s are not sticky after a full wipe, right?
If all else fails (meaning the pressure is on you folk! ), I’ll wipe the secondary drive again and start over with that one.
Earlier, @ehhen mentioned;
Now, this is not as silly as some might think.
There are occasions where simply rebooting before repurposing or re-using the same disk for a reinstallation, is simply not enough.
With some hardware combinations, one has to physically shutdown the machine and disconnect it from power for a minute or two before continuing.
This was typically a firmware based issue, often (but not always) solved with an updated BIOS.
Although a rare occurrence by today’s standards, this was nonetheless a real phenomenon; I recall experiencing this once myself with a Gen 6 system years ago.
Basically, you might have been seeing the ghost in the machine; the system was still seeing the previous disk layout which hadn’t been fully purged. 
Shutting down the machine completely, and cutting power as described, may have prevented that.
That’s all I have.
Updating to the latest available non-beta BIOS might do some distance toward preventing that in future;
I notice yours hasn’t been updated possibly since you bought/built the machine v: 0607 date: 05/29/2020.
Version 3201 2025/01/02 is available, if the following link reflects your specific mainboard:
Regards.
The drive was brand new as of a few days ago. Unless ninjas snuck in to clone it as I slept, it wasn’t.
Of course, I was trying to fix the original one, and could have made a mistake that impacted either it or the new drive. I’ve tried to speculate where that might have happened. But mostly I was just following instructions found on this site. So I’m as baffled as you are.
Yes, it’s ~4 years old, but I don’t want to risk updating the bios - I have enough trouble right now. Instead, if I’m forced to abandon the old drive, I’ll take it as a good time to upgrade the motherboard and processor.
Oh, and the machine has indeed been powered down overnight since the problem.
Thanks everybody for your efforts, and for any brilliant insights you may hopefully still have.
The suggestion was to power down and cut power (pull the plug) between partitioning operations on disks.
Powering down since the problem is immaterial.
Regards.
So it was. That seems excessively paranoid, but after this, count me as paranoid.
If the “cloned or not” debate is over, I’ll meekly mention that all three of the errors in the thread title are still present.
After removing (only) “quiet splash”, and with only the non-bootable drive in the system, I posted every step in the published grub restore sequence above. There were various errors, with at least one labeled “fatal”.
Are there any other suggestions from the collective mind that I could try?
Thank you for your patience and assistance.
You are the administrator responsible for maintaining your own system. All we can do is point you toward things that might possibly help.
I have nothing more to add at this time, except to remind you of the suggestion from @ehhen, when next you try to install the OS.
Regards.
Ok, thank you for trying.
I know you are all volunteers and deserve respect for your time. And of course I’m ultimately responsible for my own system.
I’ve used Manjaro for the last 7 years or so. It’s done what I’ve needed, and I’ve enjoyed using it. But every time I do one of the frequent updates, I cringe, and not without reason. Maybe a rolling release is not the best for me.
The silver lining is the 9950x upgrade that I’m picking up today.
Thanks again.
It’s unfortunate, but often true.
Manjaro, like any rolling release distribution, is not a “set and forget” OS such as the walled garden of MacOS – it requires ongoing preventative maintenance which only the system administrator can effectively provide.
The problem remains in that there many simply not interested in much beyond running their free applications; certainly not in reading, learning, or spending the time needed to keep their systems running smoothly.
I’m afraid Linux often isn’t a good fit for those with misplaced expectations or who won’t take responsibility for their own continued ignorance.
But, still they come. 
Presuming you meant one of these;
If you are intending to upgrade your machine with the new Ryzen, then I again suggest you update your BIOS for compatibility.
Your current BIOS is v0607 (released 2020-06-11) - There have been thirteen (13) BIOS releases since then - the current being v3201 (released 2025-01-02).
It’s quite possible (I dare say, likely) that a BIOS from vintage 2020 will not be fully compatible with a Ryzen 9 9950X, even in Windows.
Because you are upgrading your hardware, effectively it becoming a different system, this topic becomes rather irrelevant.
If you have further difficulties after successfully upgrading your hardware, feel free to create a new Support request.
Regards.
The following is a list of important BIOS updates you have missed:
BIOS v: 3201 - 2025/01/02
BIOS v: 3001 - 2024/04/17
BIOS v: 2801 - 2023/12/01
BIOS v: 2701 - 2023/03/21
BIOS v: 2601 - 2022/06/10
BIOS v: 2403 - 2021/12/16
BIOS v: 2301 - 2021/07/24
BIOS v: 2301 - 2021/07/24
BIOS v: 2201 - 2021/07/08
BIOS v: 2103 - 2021/04/28
BIOS v: 1003 - 2020/12/23
BIOS v: 1003 - 2020/12/23
BIOS v: 0901 - 2020/11/18
BIOS v: 0805 - 2020/11/16
BIOS v: 0707 - 2020/08/28
The thing is that there’s a huge difference between being interested in GNU/Linux on the one hand, and trying to escape from Microsoft Windows on the other hand.
Most newbies unfortunately fall into the latter category. And that’s a shame. 
And, it is a shame, when you think how easily they could turn it around. Spending some time to learn, or at the barest minimum - taking notes, could make all the difference.
Keeping one’s system well maintained only takes a decision to actually do it. No-one expects newer users to get everything right straight away, but please - any newbies reading this - at least make an effort.
Have I drifted a little off topic? 
