"The USB media was changed. Do not change the USB media while it is being read." appears on the LCD.
The USB media was changed while it was being read. Please try again without disconnecting.
If the start/stop button is pressed while the machine is not correctly set up or if an incorrect operation is performed, the machine stops and informs you of the error with a buzzer and an error message.
If your question was not answered, have you checked other FAQs?