This is the most common hiccup. Go to System Settings > Audio Output and cycle through the options (HDMI, Jack, etc.) until you hear the background music.
You don't need to be a Linux expert. Most features work the moment you plug in a controller. batocera iso
A great alternative that often includes Batocera in its "Games" menu. 3. Booting into Batocera This is the most common hiccup