This guide will give you a list of known solutions to use when you are having problems with GRUB.
In order to repair GRUB:
Once you entered the live mode, open terminal and type
sudo fdisk -l
The output should be similar to this.
/dev/sda is usually the first SSD or HDD. If you have an NVMe M.2, the disk will be named
/dev/sda1usually is the EFI partition, used for booting the OS in UEFI systems.
/dev/sda2is ParrotOS partition.
A mount folder is needed to perform this operation. So, in the same terminal window, type
This is the main folder. Next type
Which creates the directory used for mounting the EFI partition. This is needed for installing the correct GRUB package.
Now it's time to mount the partitions. In the same terminal window, type
sudo mount -o subvol=@ /dev/sda2 /mnt
sys folders and the
EFI partion in order to get access to the system.
In the same terminal window, type
sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo mount /dev/sda1 /mnt/boot/efi
Time to enter the system. In the same terminal window, type
sudo chroot /mnt
Once in chroot environment, type
After the installation is finished, type
exit so as to exit the chroot environment.
After exiting the chroot environment, unmount all of the partitions and folders used. In the same terminal window type:
sudo umount /mnt/dev
sudo umount /mnt/proc
sudo umount /mnt/sys
sudo umount /mnt/boot/efi
sudo umount /mnt
reboot and press enter. You should now have a restored GRUB working flawlessly.