Sometimes DSO068 might be found behaviors abnormally (like constantly rebooting, halt in a specific state) and menu can't be entered to perform factory default restoration. In this case you can do forced factory default restore by following steps below:
1 ) Power off the scope and connect PF6 pin at J6 to GND via a 1K resister.
2 ) Power up device to normal working state.
3 ) Power off device and removed the connection made in 1 ).