Check that there is no pocket-lint or other debris in the port. Something might be shorting the pins of the port. [br]
You can also try cleaning the port with a toothbrush with some rubbing alcohol on it. [br]
And/or blow on it with some compressed/canned air.[br]
Also, Look into the port with a magnifyer or use phone camera and zoom in, to see if any of the small pins look out of place.