Backup Your Wii's NAND-
Bootmii/Nand Back Up
It is highly recommended to make a NAND Backup with bootmii as it can save you from 99% of bricks. That is, if you can install bootmii as boot2. You'll need a SD Card with at least 550 MB free on it. Also, note bootmii can be picky about SD Cards so its best to avoid generic ones. The 2GB Sandisk SD Card is recommended.
a) Place the SD Card into your wii and power it on. If bootmii was installed as boot2, the bootmii screen should automatically appear, if it was installed as an IOS, then you'll have to go to homebrew channel, press 'home' on your wiimote then select 'Launch Bootmii'
b) Navigate using the power/reset/eject buttons on the front of your console and select the icon with the gears on it. If the console buttons don't work, you'll have to use a gamecube controller.
Power = Right, Eject = Left, Reset = Select
c) Now select the icon that has an arrow pointing to a SD Card but from the chip. Then follow the on-screen instructions to backup your NAND.
d) In 10 - 15 minutes, the NAND Backup should be complete. You may get a few bad blocks but any number of bad blocks under 80 is normal and fine. Once all is done, you can exit bootmii.
e) Remove the SD Card from your wii and insert into your PC, backup the 'bootmii' folder, the 'NAND.bin' file and 'key.bin' file from your sd card onto a safe place on your PC. Once these files/folders are on your PC, delete them from your SD Card. If you do not and bootmii as boot2 is installed, it will load everytime!
DO NOT LOSE YOUR NAND.BIN OR KEYS.BIN
If you were to ever brick, just copy the bootmii folder and 'NAND.bin' from your PC onto the root of your SD Card. Then repeat parts a, b & c but this time selecting the icon that points to the chip. While bootmii/boot2 can save you from full bricks, bootmii/IOS cannot! It is not recommended to use bootmii as an IOS to restore your NAND! If you can only install as an IOS, your nand backup is still useful, keep it safe.
Explanation of Bootmii:http://www.wiihacks.com/recommended-...beginners.html