1.Check if the rear panel power switch is in the ON position.
2.It may be caused by insufficient power supply, please try to connect DC5V power supply to the power input.
3.Confirm if the USB cable is broken or damaged, replace the USB cable with a new one. Use a USB cable no longer than 2 meters.
4.Try with other USB ports of your computer.
5.Check if the problem is on the computer. Try with another one.