Bricked wii??? Need help to recover

Hi there
For sometime I have had my wii running homebrew, the other day I updated to 4.2U foolishly through nintendo, since then my wii freezes after the initial safety screen or lets me through to the start menu then either hangs or will hang if I select something like settings, homebrew always crashes it although I can run games if I am quick enough to select them before it hangs.
I don't have preloader or bootmii installed

Any ideas how to fix this.

thanks

Tom

Launch Super Smash Bros Brawl. Use Smash Stack to launch DOP-Mii and have it install system menu 4.2U. You may need to install IOS 36 with fakesigning before reinstalling the system menu (fakesigning is not necessary to do this, but DOP-Mii will not run on an IOS that does not accept fakesigning).

Try to boot into maintenance mode by holding + and - at the health screen, while holding + and -, push A. See if this have any effect on your systems instability.