Try on 3490 with original 3597 FW (3597 boot.bin, resources.bin and fw_all.bin), flash go OK but after restar, stuck on black screen, the same situation like when we try to flash 3590 FW on nuvi 3xxx series.
Maybe will some other have more luck when he flash on nuvi 3790, but i think that no go becouse 35xx series have bigger screen.