Thanks, Fishr --
And sorry for the delayed response (keep being diverted by higher priorities).
make do --
First, tell us WHICH Mac you have and what year it was made.
MacBook Pro A1708.
Do you have a bootable USB flashdrive (with the installer on it)?
No.
That can make things easier.
You may need access to ANOTHER, WORKING Mac to create one.
Do you know how to boot to internet recovery?
(Power down all the way off/press power on button/immediately hold down "command-option-R" and keep holding down until internet symbol appears/if you are using wifi, you may need to enter your wifi password).
Can you actually do this?
Have you tried it?
If not, try it right now and get back to us.
I surely had tried that!
Do you have either a USB flashdrive 32gb or larger,
Yes, I have a 62gb USB and assume that one can get an adapter to fit it to the MacBook port.
OR an external hard drive around?
WHY I asked:
If you can't install to the internal drive, you could install to the EXTERNAL drive (or flashdrive) and then CLONE THAT INSTALL to your internal drive. This will work beautifully.
Correct me if I'm wrong, but does this mean that after all that I will have two "volumes" showing up in the Utilities: the original one, which I wasn't able to delete fully but would be able to deactivate by deselecting, and the one from the flashdrive which I'll be able to "install" and activate by selecting?
I could have your Mac up and running
in about 3 minutes.
But that's because I have BOOTABLE EXTERNAL DRIVES that can boot any recent Mac.