What should I do if there is no picture or sound from an external device?

Make sure the connection to the device is correct and that all cables are fully inserted. Remove and reconnect all cables connected to the TV and external devices, trying new cables if possible. Confirm that the correct input source has been selected (> Source). Perform a TV self diagnosis to determine if the problem is caused by the TV or the device (> Settings > Support > Self Diagnosis). If the test results are normal, reboot the connected devices by unplugging and replugging their power cords.