However, as part of their attempt to annoy homebrew users, Nintendo updated the lowest level updateable component of the Wii software stack: boot2 (part of the system bootloader chain). Homebrew users have been using BootMii to patch boot2 in order to gain low level system access and recovery functions (running Linux natively, fixing bricks, etc). The update hasn't hindered this, as users can simply reinstall BootMii after updating (it is compatible with the update). But there's a much bigger problem: Nintendo's boot2 update code is buggy. Boot2 had never been updated in retail consoles until now. During BootMii's development, its authors noticed that Nintendo's code had critical bugs and could sometimes permanently brick a console by writing incorrect or unchecked data to flash memory, so they decided to write their own, much safer flashing code. Now, Nintendo has pushed a boot2 update to all Wii users, and the results are what was expected: users are reporting bricks after installing 4.2 on unmodified consoles. Nintendo is currently attempting to censor posts and remove references to homebrew.
It is worth noting that the new boot2 does not attempt to block anything or offer any additional protection or functionality. Its sole purpose is to simply replace current versions which may or may not have been modified with BootMii. Another interesting tidbit is that Nintendo is not believed to have any method to repair this kind of brick at a factory, short of replacing the entire motherboard."