If you cannot control an HDMI device using the HDMI
Link buttons, try the following solutions: 
- Make sure
all necessary cables are securely connected and the power is on for
the projector and connected video sources.
 
- Make sure the cables meet the HDMI standards.
 
- Make sure the connected device supports the CEC
standards.
 
- If you connected a new device or changed any
connections, you may need to restart the device.
 
- Connect no more than three devices that support HDMI
Link at the same time.
 
- If you have connected a speaker or receiver, set the
output to PCM.