If you black screened while actually playing then it's more than likely your bluetooth module. You can sort of confirm this if you cannot switch the Wii on using the remote. Do be aware that they can unseat themselves as well as break down.
The Wii will wait for the bluetooth to enable before completing the boot process, if it doesn't enable then it'll just sit there on a black screen.
If the module is actually broken or unseated itself then this has little to do with bootmii and updating system menu wads and no matter which IOS you install or remove you'll never have a working Wii.