If your system becomes unstable or "bricked," you can restore your previous NAND dump. Warning: This process can be dangerous if interrupted. Ensure your console is plugged into a charger.
Ensure your 3DS is running GodMode9 (a standard tool in modern Custom Firmware setups). 3ds nand download install
Always keep a copy of your unique nand.bin and essential.exefs. If your system becomes unstable or "bricked," you