Attention, don't install preloader (which works on 3.2, 4.0 consoles only)
install Priiloader instead.
install this:
1. HBC + bootmii as IOS
2. priiloader (+ enable some patches from its options as your own preferences)
3. cIOS if you intend to use USBLoaders
When you install a bad WAD, now that you have priiloader you can always go to priiloader menu (keep reset button pressed when booting the console) to launch HBC and bypass the banner brick, but that's not the way to do it.
you should prevent it instead of fixing it.
to test your animated banner, and verify the WAD you install is not a fake/scam (it could be a system menu dummy file disguised in an appealing game!), you should test and install it on a NEEK emuNAND.
NEEK is a way to launch the console using a copy of its memory, the copy is loaded from SD (sneek) or USB (uneek) and acts as if it was your real console's memory.
if you brick, it only brick the copy, not your real console.