The BIOS is the heartbeat. Finding it isn't just about playing a game; it’s about making sure the machine still has a heart to beat with.
and check the /gm9/out folder on your SD card. The files boot9.bin and otp.bin should be created. Nintendo 3ds Bios File Download
What is your device running (Windows, Android, macOS, Linux)? The BIOS is the heartbeat
The most reliable and legal way to obtain these is by using custom firmware. How to Legally Get Your 3DS System Files To do this, you need a 3DS with GodMode9 installed. Nintendo 3ds Bios File Download