A banner brick occurs when the user installs a channel with an invalid banner (wrong image size). With this type of brick the system will freeze after the Health and Safety screen and may display a "System Files are Corrupted" error message.
Fixing this brick
Since boot2 is intact during a Banner Brick, any user who owns a pre Q4 2008 Wii with BootMii installed (as boot2) can access BootMii regardless of any corrupt WAD installed. From here they can access the HBC to uninstall the broken channel using AnyTitle Deleter.
Users Without BootMii installed as boot2 and Priiloader/Preloader may use the BlueBomb exploit to launch the HackMii Installer, which will enable access to the HBC, so a similar recovery procedure can be used as described above.
NOTE: Uninstalling the incorrect channel may lead to further damage, so users should be careful.
Cause of this brick
A banner brick is caused when a channel with a malformed banner (icon), is installed. Due to the poor error checking of the System Menu, the system menu can't handle the corrupted banner, so it crashes and thinks that it is a file corruption.