It installs to an empty slot (236) rather than overwriting original system files.
Many installers (like the d2x cIOS installer) require IOS236 to run properly. ios236 installer wii
Ensure you are using a standard SD card (not SDXC) if possible, as older homebrew prefers 2GB or 4GB cards. Is IOS236 Still Relevant? It installs to an empty slot (236) rather