To connect your controller for the first time:
You should see an image of the SHIELD controller on your TV.
If not, open the SHIELD Accessories app, located in the settings row of the Home screen.
Touch the NVIDIA button on the SHIELD controller. It will flash, indicating that it is in connecting mode.
The controller should connect after a few moments.
If the controller did not connect:
Make sure the controller is unplugged.
If the NVIDIA button is not flashing, touch and hold the NVIDIA button until it flashes (3 seconds).
If the NVIDIA button does not start flashing or turns off, charge the controller and try again.
To charge the controller, connect it to one of the USB ports on the back of your SHIELD with the included USB cable or connect it to another USB power source.