This troubleshooting guide applies to all HDMI-related devices, whether it's a computer, TV, etc.
HDMI is supposed to make it easy to connect all your devices together with the use of one cable for both audio and video. To do this, connected devices must be “licensed” to communicate with each other through a standard known as HDCP.
This ability to recognize and communicate media and devices is referred to as the “HDMI handshake.” If the handshake doesn’t work, that means the HDCP encryption embedded in the HDMI signal is not recognized by one or more of the connected devices. This usually results in you not being able to watch your movies or play your video games.