For us to isolate the issue, could you tell us if your Roku device is powered by the USB port at the back of your TV or by a wall outlet? If you haven't tried any troubleshooting steps yet, you can try the suggestions below.
Verify that you are using the USB cable that came with your Roku player
If you are using any USB cable other than the one that came with your Roku player, replace it with the one that came with your Roku player.
Try a different USB Port
Some USB ports have different power characteristics. Connecting your Roku player or Roku Streaming Stick to a different USB port on your TV may resolve the issue.
Connect power to power-outlet
Using the included power cord and power adapter*, connect the Roku player or Roku Streaming Stick to a working power outlet in the wall.
Connecting to a power outlet in the wall has the additional advantage that your Roku player will not need to power up every time you turn on your TV. This means your Roku player will be up and running faster than it would be connected to a TV.
In some cases, using a different USB cable and power adaptor from mobile devices may help resolve the issue. Try giving it a shot.
Furthermore, please let us know how are you powering the device. Is it plugged into the TV USB port or to a wall outlet using the Roku provided cables? With more information, we will be able to assist you further.