Press any key for 3 to 10 seconds, and release it when you hear a short 'beep' and see the corresponding green light flashing. Press the same button again for 3 to 10 seconds within 4 seconds. And release it when you hear a long 'beep' and see the corresponding green light flashing. When you hear a short 'beep' and see all the lights flashing blue and green alternately, it indicates that the factory settings have been successfully restored.