You probably need to set up the OpenUPS board again. Start with downloading the OpenUPS software:
Once the software is installed, click on the "Settings" tab of the pop up window. Click on the "File => OpenUPS" button to load and replace the settings files.
The Turtlebot 3 Burger mobile education base is a lightweight, compact, low-cost and customizable ROS-based mobile robotics platform. It is the perfect solution for anyone looking for a fun way to support their robotics programming workshops, but also for robotics apprentices, designers and developers.
The resources available for Turtlebot3 are very numerous. Here is a link to all ROS installations for TurtleBot3