@AsItLiesAhhh sorry may have misunderstood your wording. You don't use 'edl mode' to unlock the boot loader. You DO use edl to flash the engineering abl to then use FASTBOOT to unlock the boot loader.
But that may have been what u meant. So yes, use edl to flash the eng abl, then use it (fastboot) to unlock the boot loader. Yes, it will work with 409n, but any time u unlock the boot loader, user data gets wiped. Nothing you can do about that.
Today i successfully got crossflash 409n 30e to 405ebw 30d but imei no is 00 what i do i have no backup of anything i tried 409n 30e original kdz but same problem plz helpAs far as I know u can, I've had both 409n 30e and an older version of ebw on my device - think it was 30b UK. Although there is some talk recently on tele group indicating LG has done some things with newer roms to stop crossflashing. I'd check there first.