it's possible that the wii itself is fried, but the power converter is almost definitely fried. The way to test if the power converter is fried is:
- get a multimeter(they sell them at Home Depot, Lowe's, Radio Shack
- plug the power converter into an appropriate socket (110V American)
- make sure the multimeter is set to test voltage, in the correct range (i.e.- up to ~100-220V)
- connect each tip of the multimeter, one to each tip of the power converter that plugs into the wii
if the needle (or digital readout) says it's anywhere from 100-120V, it sounds like your power converter is fine and it would be the Wii that is fried
if the power converter is fried, it is still possible that the Wii is fried as well. So buy a power converter from a place that has a good return policy (since if you buy a new Wii, the power converter comes with it)
Note: You may be able to find an electronics repair shop that will check the power converter for you for free, so that you don't have to buy a multimeter.