I know this won't help your particular problem or isn't even a proper answer, but is there any way you can try a different kind of connection between your Wii and TV ?? Maybe the scart or something ??
Just in case, god forbid, the Wii isn't working properly. At least if you do get a picture with this method you nkow the Wii is OK and the Wii to TV connection needs attention.
Worth a try at least.