Rescue System
When a system fails to boot, the "Enable/disable rescue mode" feature lets you access the hard disk.
The rescue environment relies on Rescatux. After switching it on, boot up and start by identifying your original hard disk with this command:
lsblk
You should spot your hard disk devices, for instance /dev/sda1, which ought to correspond to your drive’s size (e.g., 50 GB).
Next, simply mount the device to a directory like /mnt by running:
sudo mount /dev/sda1 /mnt
Carry out any necessary changes.
Once you have finished, disable rescue mode.