I have a bricked "new" 3DS XL and a fine old 3ds XL. When I power on 3DS, it shows blue screen of death bootrom error 00F800FF F8F8FFFF FFFFFFFF.
From https://www.3dbrew.org/wiki/Bootloader#Error_Codes that mean "Both the firm0 and firm1 partitions are corrupt (failed signature checks)".
I...