I am trying to hack my friend's wii and he has firmware 4.2U. I got bannerbomb to run and installed HBC and BootMii as boot2 and IOS. I booted into BootMii and backed up the NAND. After that the wii just goes to a black screen when I turn it on. If I remove the SD card it will boot into the Wii menu. If I remove the NAND.bin and key.bin from the SD card, the wii will then boot into BootMii again. There seems to be a problem with having the nand.bin and key.bin on the SD card. I know I can continue from here and go on to the remaining steps of hacking the wii. My only hesitation is if I mess up the wii I won't be able to boot into BootMii with the nand backup on the SD card. Anybody have any ideas why this might be happening?