Hi Floyd,
Seems like you’ve tried everything I would suggest, but not to insult you, I am assuming that you made sure that the TV selector was set to the proper inputs? (HDMI TO HDMI, AV TO AV,…..) I have done the same thing, only to realize I hadn’t selected the correct input.
I have repaired several Wii U consoles with this same issue, a couple were the HDMI chip, (available online) and several HDMI ports, but sad to say, nothing like what you are describing. Most always you can get the AV cables to work.
One more question, when you connect the console using the HDMI cable, does it have sound?
Thanks.
J.K