Rescue System

When the system fails to boot, the "Enable/disable rescue mode" option gives you access to the hard drive. 

The rescue system is based on Rescatux. Once enabled, boot it up and locate your original hard drive by running:

lsblk

You should see disk devices like /dev/sda1 that correspond to your drive's size (e.g., 50GB).

Then, mount the device to a folder such as /mnt using:

sudo mount /dev/sda1 /mnt

Make any necessary changes.

When you're done, disable rescue mode.