John Abnarthy wrote:

I think I found the issue(s). Doesn't make sense to me, but I have
actually heard of folks running into it. It seems that even though
these are nearly identical laptops, I can't either swap batteries
between them or even power supplies.

The batteries are not just encapsulated chemical packs. They also
contain logic. It's possible the battery is coded for use within a
range of models or within a family of models. I haven't run into this
but then I always buy replacement batteries that stipulate they are for
the laptop/notebook for I am buying them.

The spare I bought had Win 10. Since I'm not ready to use it, I just
pulled the drive and replaced it with a clone of the drive in my
original laptop. That drive has dual boot with either Win 7 or Ubuntu
selection at boot up.

Then you are violating the Windows 7 EULA. You know better. You only
get one license to use on one computer. If it is a retail license (not
likely with laptops) then you can move the license to another computer
but then you can no longer use it on the prior computer. Since it is
likely an OEM/System Builder license, you aren't allowed to move it
anywhere after having installed it. The OEM license sticks to the first
computer on which it gets installed.

https://www.microsoft.com/en-us/Useterms

Just pick the OS and version of the one you are copying/cloning to your
2nd computer (the used one that you just got).

Moving an HDD between computers does not make the 2nd one the same
device as the first one from which you yanked the HDD. Putting a cloned
drive into your 2nd computer means you are duplicating the OS license
but you only have one license so you are violating the EULA.