GRUB Refusing to start in console mode...
 

I have done everything I can find on the internet, changing/ removing files like grub.cfg, or editing /etc/default/grub, to force "text" mode launch, etc... Absolutely NOTHING is working, (I have two partitions, Linux Mint the one I use most, and Manjaro KDE).

The Grub2 menu I see, has the manjaro logo on the bottom right, giving me the impression this is Manjaro's fault, so I mounted Manjaro, chroot'd into it, and did the same configurations on it's files, then ran the command to updare grub.

I really have NO clue, why it won't just work. It's extremely irritating...

While you're at it, I also want to use startx to launch my WM/ DE, but when I uncomment the line in the file default-display-manager, it just refuses to load the system.

^^ Maybe you can see where I'm going, with starting things in terminal mode, and manually loading them, vs. auto-GUI/ auto-Load.

And we're all supposed to be mind readers ?.
No indication of what you did - or why you did it. Flailing around doing is hardly the most sane way to effect a change.

Mint (currently) uses upstart - Manjaro presumably systemd as it's based on the Arch repos. Not even similar - no chance the changes will be common.
Read this for upstart background - see section 4.7 in particular for runlevels.
The Arch wiki has an excellent systemd article, covering targets equivalent to the old runlevels if I recall correctly.

For Manjaro, try this:

you should really give us some more info about your setup.

after that:
what exactly doesn't work?
what are you trying to achieve, and what did you try to achieve it and how did it not work?
while we're at it? really?
but nevermind; question is again, what line in what file? and how does "it" (?) refuse to load the system?

I guess it could be possible that some features were removed from your grub.

Generally I'd say press the space bar at some point in the boot process to edit it.