Insert a USB flash drive into one of the host ports on the back of the unit (or the front panel if convenient).
This wipes all user data and reloads the original factory sounds, styles, performances, and operating system resources. This is the "nuclear option."
: While holding down the [SHIFT] button and the [MENU] button, turn on the power switch.
Select this new package to load the factory Operating System and "Musical Resources" (Styles, Sounds, and Performances).