Picture won't show on the tv

Double check the wires that is ok and completely ok without worn or damage on it.

Try to reset the adapter using this link

http://en-americas-support.nintendo.com/...

If nothing work you can try to ask in a local repair center to diagnose what is burned inside the wii board. That might be a coil or in the worst case have GPU damage an need to replace the GPU chip.... You must have special machine to replace this chip ....