With a brand new Wii chances are high that you've got the D3-2 chip which prevents the drive from reading backup discs. This is probably why your discs aren't reading. There's no workaround for that and you'd have to load from usb.
cIOS38Rev15 was a bugged revision: Downgrade to rev14 or update to rev17.
You should check out the softmod guides in the Tutorials section. Find your firmware version in Wii Settings and follow the 3.1-4.1 guide or one of the 4.2 guides. You'll find the downloads and instructions you need in those guides.