Warning: there's a couple "fun" ( aka "new to me") things in this LONG email. SUMMARY 2-lines-below:

1) on reboot, an initramfs prompt, errors only seen briefly as boot screen overwrites it.  Needed fsck.

2) later when things got worse, my solution followed by a different error message re: "environment block too small".

the LONG story:

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/sataII ... 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....

( 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 worked every time (a few times), nothing scary for an ex-unix-sysadmin, followed by

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). 

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 exportedthe old history to study, 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 (this) 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