Warning: there's a couple "fun" ( my definition for "new to me") errors/areas
in this LONG email.

Months ago i managed to move wife/maureen's desktop environment to Mint(ubuntu underneath).
Usage: firefox,gmail  (almost nothing else of note. This took some persuading, but desktops are such a fallback these days......another topic for another day)
 
DESKTOP: 10?yr-old Gigabyte motherboard with sata2 ... 4 ports. I only use 1 sata port.
I "gave" it a $90/bestbuy 256g SSD Samsung months ago for /dev/sda
which ran well+fast of course, turns out the SSD is actually still fine internally.

A FEW WEEKS AGO, the "hint" symptom (1 of 2 in this long story)  for disk woes was....
(well, it started crashing occasionally, then)
ON BOOT, it would sometimes STOP at this prompt

initramfs>

and with good eyes as the boot-attempt screen(s) would fly by and return to above prompt,
I discovered I could fix it with  (  actually i did not use the "-y" prompt, but it's the same fix either way)

initramfs>  fsck -y /dev/sda1

Which would fix a few things, nothing scary for an ex-unix-sysadmin, and

initramfs> exit                       ######## would allow it to boot and be OK for days or so.

I taped THAT magic (fsck...) onto a paper mini-sign on the PC for another rainy day.

TODAY, the crash was followed by not booting (random results, kernel panics or bios/grub waiting).  Worse (not that we care!) near the end of this story,
          the Patriots gave up cool kickoff return with a lead and 0:04 left.
But timing-wise, I'm glad I had a few hours in the living room to debug all this.

So I brought the SSD to my other living room desktop (not booting FROM it...)
checked SSD with   sudo smartcl -a /dev/sda           #### AND ITS FINE.

I moved the SSD "back" to wife's PC on another SATA port.
It's fine! (motherboard deteriorating i guess....but might last another decade).
  I did run into.... ("created" by moving the disk i assume)
                             .... a boot/warning error NEW TO ME:
On initial boot  a WARNING ERROR on the early/black screen
          (similar to where initramfs>  shows up..just before that i think)
"warning: environment block too small"

was actually ignorable (after a few secs, boot marched on to kernel/logo).
But I found "it's a thing" and the error appears solvable with first google hit suggesting

linux user# sudo rm /boot/grub/grubenv   # or "mv" it somewhere.old; 1024 byte file.
...............# sudo grub-editenv /boot/grub/grubenv create

and reboot. Seems good now except  (new i think; probably from the sata port move?)
there's a ONE MINUTE wait on the initial boot with the Mint logo flashing.
Final things-to-inspect:  (no need to "fix" /etc/fstab
               which of course does find the disk parts ( just / and swap) by UUID
and /var/log/syslog  ( I have exported it all, i think the disk errors stopped. )
=========================WRAPUP
Haven't solved this learn-all mission yet, but...hope to make it to WLUG THURS EVE
and i just thought of a topic. Trick is knowing where to start such a story/tutorial;
I'd try to skip over BIOS and sata/disk/etc basics, the fuzzy parts for me
involve    "initramfs"  ...  grub .....   and maybe that's it for me.  

Desired talk/take-home:      linux BOOT steps you don't want to know.  -doug