Install IOS50 v4889 IOS50-64-v4889.wad & then
System Menu 3.4 for your region
Using cboot2 Wad manager mod cboot2_wadmanager_1.5_mod.zip
Drop the cboot2 archive contents directly to your formattted SD, then copy the two wad files to SD:\wad
You'll need a gamecube controller.
If you can get HBC to run you might be able to use the Wiimote and any version of Wad manager to install the wads.
Your Wii is trying to run off a stub IOS50, if you had not installed Bootmii/boot2 then you'd be packing your Wii up to send back to Nintendo.