Did he, by any chance, install priiloader v0.5? Priiloader v0.5 has a nasty bug in it (or rather, the HBC has it) that can brick your wii. Anyway, did he install bootmii as boot2, or only as IOS? The disc drive light will flash twice when you power on the wii, if you have bootmii as boot2. If you have bootmii, you can use a NAND back-up to restore it, or if you don't have one, you can use this guide: Fully Brick, Bootmii/boot2 installed but No Nand Backup? Solution Here!. If you don't have bootmii as boot2, you could try savemiifrii.