I am new to the homebrew stuff and I get the error when I try to open the gecko OS .elf file from an sd card that says "it's not a valid wii file". I tried the .dol file instead and the wii goes black and doesn't respond. Is this going to mess up the wii?
The DOL file should work. Is the screen completely black? If not, try removing any GameCube Memory Cards, if they are inserted. If that doesn't work, I would suggest deleting those files off of the SD card, and trying these...
http://www.usbgecko.com/files/geckohb9.zip (http://www.usbgecko.com/files/geckohb9.zip)