You can download from this page pre-configured Linux image for single board computers.
CORE2-ROS image - Linux + ROS image for single board computers
Customized Linux operating system for ASUS Tinker Board and UpBoard with pre-installed ROS packets, Husarnet, and software to communicate with CORE2 real-time control board.
NOTE for ROSbot 2.0 PRO users
Make sure that you have right BIOS settings:
Connect a keyboard and a monitor to the robot and turn it on
Press ESC during system booting to enter a BIOS settings