To provide a bit more background to @roypen’s answer,
GRUB_TERMINAL_OUTPUT="console"
sets the grub menu to text-based console. I think this is done for compatibility reasons.
@major, all the commands and parameters you’ve tried are for graphical output of grub, they simply don’t work in console mode. They will in gfxterm mode.
Also just commenting out GRUB_TERMINAL_OUTPUT="console" will have the same effect: grub will use gfxterm mode – although providing the option explicitly is a cleaner solution.
One more thing I personally do to make grub menu more pleasant is install and activate grub theme. Install it with
sudo dnf install grub2-breeze-theme
and then add to /etc/default/grub this line:
GRUB_THEME="/boot/grub2/themes/breeze/theme.txt"
and don’t forget to change mode to gfxterm, as suggested by @roypen. Regenerate grub.cfg menu – again, @roypen’s provided the commands to you – you need to do it after every change to /etc/default/grub.
The result won’t be astonishing, but it’ll be prettier than text console or default gfxterm output.
As far as I know, you can also find other themes for grub2 online – maybe prettier ones, – but they aren’t packaged in Fedora. Still they are easy to use if you want to.