It should be fixable. See if you can get into maintenance mode, if that works you can fix it from there. If maintenance mode does not work you will need to fix from the recovery menu, a modchip is likely required but try to load the autoboot B.L.I.N.D. disc first, patched with iospatcher to ios80. If your lucky he has a patched system ios with dip. Otherwise if no patched system ios, install a modchip, try B.L.I.N.D. again. If B.L.I.N.D. still does not load via modchip you will need to use the Swap Disc PWNS method to load super smash bros brawl PAL from the recovery menu.
If maintenance mod load, run the hackmii installer via exploit (try letterbomb, possibly need game exploit). Install HBC, Bootmii, make nand backup. Install priiloader, then go to the wii settings and do a system format from the wii settings.
You can fix it.
Let me know your progress and I can give more help if needed.