Some HDMI cables are basic, standard cables; some have extra functionality built in, such as Ethernet. Make sure you are using a basic, standard cable, that is, unless HDMI port 4 calls for a special type of HDMI cable; in that case, make sure you have that special type of HDMI cable.
Also, try a known good cable, that is, one that works in another HDMI port. In other words, plug your device into the TV, into a known good HDMI port. Once you have established that it is working correctly, unplug the HDMI cable from the port it is in, and plug it into HDMI port 4. In this way, only the HDMI port changed; everything else stayed the same.