3DS:BootROM 8046 screen

The bootrom may show a blue screen with yellow text if it fails to find a suitable firmware to boot into. The most common reason this might happen is due to all firmware partitions being corrupted.

Example text
BOOTROM 8046 ERRCODE: 00F800FF F8F8FFFF FFFFFFFF 00000000 00000000

Fixing
If this is due to a software problem such as corrupted firmware partitions or corrupted NAND header, this can only be fixed with an ntrboot-compatible flashcart or a hardmod.

If this is a hardware problem such as a faulty NAND chip, you most likely need to replace the motherboard.