The above error may arise from the following reasons:-
1. When power supply is off.
2. When MOTOR USB is not properly connected.
3. After switching on the Machine, Motor USB eject by mistake.
4. When loose contact of motor USB cable with machine.
To resolve this kind of problems, go through the following steps :-
1. First of all switch-off the machine switch and machine software.
2. Secondly, check all the USB connections whether are properly connected or not, if not then reconnect it or plug in it properly.
3. Lastly, restart the machine.