OEM Image Setup

I’ve been trying to create a new OEM image for the herelink system. I’ve followed the instructions on Ubuntu however when I mount the raw image I don’t see the file structure I was expecting. I thought I’d see /system/etc however all I see is lost+found, media for directories and oem.prop for a file. media only has bootanimation.zip. What do I need to do to get access to these?

I’m thinking that I have to create these. I’m having trouble finding the location of the settings I need. Where can I find the radio settings and button mappings etc?