If you are experiencing problems with GRUB, such as the boot menu being corrupt and unusable, you may need to disable the graphical boot screen. To do this, become the root user and add the following line to the /etc/default/grub file:

GRUB_TERMINAL=console

Refresh the grub.cfg file by running the following command with root privileges so the changes will take effect:

grub2-mkconfig --output=/boot/grub2/grub.cfg

To re-enable the graphical boot screen, remove the newly added line or comment it out by inserting the # character at the beginning of the line.