Use the following list of possible causes as a guide. Some items may not apply to your device. Work down the list
to eliminate problem possibilities.
If there is a cable from the adapter or system unit to the device then verify that the cable
is seated correctly at both ends before replacing parts.
If the device has its own power source then power off and power on the device. Verify that the device has power before replacing parts.
Try a different device in the same USB connection. If the different device functions properly then suspect that the original device
is either not supported or failing.
If you have determined that none of the above are the cause of the problem then work the failing item list.