For mobile emulation (like the Delta emulator on iOS or the DeSmuME/MelonDS cores in RetroArch), file placement is highly strict.
Once you have secured your legal ndsbiosarm7.bin file, you will need to place it in the correct directory of your chosen emulator. Here is how to configure it across the most popular platforms: 1. MelonDS (PC, Mac, Linux, Android) ndsbiosarm7bin
But Elias had found a discrepancy.