Do you have boot2 bootmii?
You need one of these.
If you have them, try a system format
If you do not have bootmii boot2, or priiloader
Reinstall system ios and system menu, then install priilaoder
Follow this guide- http://www.wiihacks.com/bricked-wii-...brick-fix.html
If your issue persists after that guide, try a system format.
You should backup any important savegame using savegame manager prior. The format will remove them.