Ok I Just went back over this thread and noticed something.
In your screenshot of your bios files, one of them is incorrect.
You have a "sega_100a.bin" file, this one is wrong.
You need the one named "sega_101.bin".
If you already have a bios file from somewhere else with the name "Sega Saturn BIOS v1.01 (JAP).bin" rename it to "sega_101.bin"
Edit:
God I wish we were allowed to openly upload bios files for people, this would make life so much easier.