What system menu wad did you install? What firmware are you on?
Are you sure it immediately boots to black screen? No health safety info?
Many things are able to be fixed.
http://forums.afterdawn.com/threads...from-a-wii-brick-precautions-included.663263/
http://savemii.net/
And if you are low level bricked I may actually be able to help but you will have to purchase some tools first.
Between 2008-2011 I made a pretty small fortune (small fortune defined by less than $250,000.00 but more than $50,000.00 US) repairing low level bricked wii consoles. People from all over the world sent me their "broken" consoles (as long as I paid shipping) for free. I fixed them and later sold them. I flooded ebay and for the last bit of them I made a deal with Gamestop and sold over 300 consoles to them.
Lol, enough about me. If none of the other solutions work for you and you have fully determined you have a low level brick, hit me up on pm and I will tell you exactly what you will need tool wise. ah hell tools: tri wing screw driver, small precision screw driver set (small set is fine),
universal 48 pin tsop nand flash clip, matrix mtx spi nand flasher v1.0, some small pieces of wire, a little solder, a soldering iron, usb gecko/or equivalent, and tweezers of course.
Then I give you a clean dump and after you get the keys from yours you will be good to go.
I can walk you through this completely if it is needed. I also have the correct software to use with the matrix to dump and re write to your nand.