This step requires a host PC running Linux.

• download the required disk image file

• Connect a USB thumb drive to your pc

• Run command: 
  lsblk

• Identify your drive (usually /dev/sdX, X can be different for each system) 

  • NOTE: SATA HDDs & SSDs also identify as sdX so be careful not to corrupt your data.

• unmount your drive from the system

  • ususally will be: sudo umount

• Run command:
  sudo dd if=${path/to/image/file} of=/dev/sdX bs=1M status=progress; sync

• Wait until dd finishes and you get a prompt again, safely eject the USB drive.