Where are you grub?
 

Found nada in search... Want GRUB to appear before linux is launched - but on single boot system it doesn't appear first. What is the key that makes grub appear first? These MUST be one...

TYVM

You may need to edit grub.cfg for that.

TYVM. I can't even get mint to display the Terminal unless using compatibility mode, so THAT is how I must boot it... if grub not visible CM won't be possible, so, unfortunately your point is moot.

Even Windows has the F8 key.

On any system that uses grub, there should be a root-level /boot directory which contains it ... and, its configuration file.

One of the many options of Grub is to omit displaying a boot-time selection menu entirely ... to immediately proceed to a particular selection, without presenting any choice. I surmise that this is what has been done in your case.

Boot with installation media and edit grub.cfg or whatever else you need to fix. There might be a key, try E.

Well, it was a default Mint Rosa install (not dual boot) and grub doesn't appear like the live DVD. If I can get it into CM then I can edit the grub. Without CM and grub customizer I don't have the editing ability to do what needs to be done.

You need to edit the /etc/default/grub file as explained in detail at the link below about half way down the page. Change it to comment out the two lines below by placing a hash mark at the beginning of the line as shown:

if you see this
then you have a PROBLEM

now if you want to have a menu of options like booting from a previous kernel or in a "safe" mode

then there should already be a 3 second countdown

if not
then as above
"/etc/default/grub"

and rebuild the bootloader
or also edit the grub.conf on the boot partition

You can't get a terminal? That makes no sense. Mint has an x-based terminal program, although I don't know what they use. It should be listed in the menu somewhere. If you want a full terminal outside the x-windows system, use ctrl-alt-F1 (or any F key other than F7). Ctrl-alt-F7 should get you back to the proper runlevel for x-windows. I think you're trying to go down the wrong road for what you want.