This is how I fixed my banner brick today:
Problem: Installed bad wad created with WADder
Banner brick type: black screen
System: Wii v4.0u
Drivechip: YAOSM v2 (not autoboot)
Trucha bug: Not available
Bootmii: Not installed
Preloader: not installed
Third party GC controller (I.con)
I could not:
Use any preloaded (not installed)
Boot the Universal Nintendo disk (or any custom disk)
Boot any disk that been scrubbed/trucha signed
Boot SSBB NTSC to perform the smashstack
Boot any original wii disk
What I could do:
I downloaded Bootmii ( Wii BootMe - WiiBrew )
This tool let you modify games ISOs so they autoboot
I managed to autoboot Super Smash Bros Brawl PAL
I could not use the smashstack bug with this version, but it is a great game to use to fill your Wii memory.
So this is that I done:
I played a few games, tried a few things like stage builder, and also save tons of replays.. but all this took so much time. (12+ replays to fill 1 block) I had to find something else. So I noticed that you can take snapshots during the game. 1 picture = 1 block. That was perfect. Within a few minutes I filled my Wii memory up to 99%.
Now what... I read on another post that certain games will bring you to the data management screen if the wii is full. such as the series MySims.
I got a copy of this game, made it autoboot then started it.
It brought me to the data management screen but I ran into another issue:
I could not use the banner bomb to restore my Wii.
As soon as I was entering the banner screen, the Wii was freezing right away, probably for the same reason that my wii wasn't starting.
I could still access the save files so I could have probably tried to find Lego Indiana Jones and attempt to run the Indiana Pwns exploit, but I didnt have this game and something else caught my attention: the Wii setting screen was available. So I went there and used the "format Wii memory" option.
I lost all my stuff but now my Wii is working.
So here are the basic steps:
1. Boot in the recovery menu to start an autoboot game (SSBB), either with savemii, or with a GC remote
(I found that the proper way to successfully do this is by turning off the Wii, hold the 4 directions on the GC then power on the wii by inserting the disk in)
2. Fill the Wii memory with game snapshots
3. Try booting TheSims kingdom, if the game don't prompt you do go to the management screen, this means that the wii is NOT full enough. Stop the game and try to fill it more with another game. (If you played the game before, it will most likely not work as the game don't let you manage the saves, it only overwrite old or create new ones. )
4. When you successfully get to data management, there you can fix the wii with banner bomb, Indiana Pwns, or Wii format.