System Rescue Procedure

If the system cannot boot, the "Enable/disable rescue mode" option gives you access to the hard disk. 

The configured rescue system employs Rescatux. Once enabled, boot into it, then locate the original hard drive by entering the command:

lsblk

You will see storage devices listed; for instance, /dev/sda1 should correspond to your hard disk's capacity (e.g., 50GB).

Next, simply mount that device to a directory, such as /mnt, with the command:

sudo mount /dev/sda1 /mnt

Make any necessary modifications.

When finished, disable rescue mode.