Some TVs have an HDMI cable test. Some models only have this test after a software update, and older models do not have it. If your model does not have this test or is not connected by HDMI, skip to the next step. The test is designed for HDMI cords less than 6 feet long and may not give accurate results on long cords.
To perform the test, make sure the TV's source is still on the HDMI setting for the cable you want to test.
You can find the Self Diagnosis in the Device Care menu. Navigate to Settings > Support then select Device Care > Self Diagnosis > Signal Information > HDMI Cable Test > Start Test.
If the test says the cable is bad, replace the cable. Service is not required.