Turned on my Apple TV and nothing shows on HDTV. White LED light illuminates, I can connect to it via Mac OS X and iOS devices. Just shows nothing on screen. HDTV shows message no signal detected. Plug the same HDMI into another device and it works perfect so I know the cable and TV are fine. Is there a setting or feature to turn off the HDMI port or is my Apple TV dead? Its a new 4th gen model and only one year old. My other 4th gen Apple TVs work perfectly fine. Any thoughts?