Are you sure that your BH16NS40 drive is a service code (SVC) NS50 drive (basically, unless it clearly says SVC NS50 on the label, your drive is a normal NS40 drive not an NS50)?
If your drive is a normal BH16NS40 (not one with the NS50 service code) then you can't crossflash it to an NS50 class drive. NS40 and NS50 drives use different hardware. Only NS40 drives which say SVC NS50 on the label can be flashed with a NS50/NS55/NS58 firmware. That is because NS40 drives with SVC NS50 are actually NS50 type drives not NS40, even though for some idiotic reason LG confusingly enough still branded them as NS40 drives (but on the label they say SVC NS50)... Any other NS40 drive that doesn't state SVC NS50 on the label, is a standard NS40 drive, i.e. a true NS40 drive, not an NS50 drive, and none of these can be crossflashed to an NS50 type.
Also note that firmware dumps made with DevilsClaws's flasher are raw dumps, and they cannot be flashed to a drive without first manually processing the raw firmware to turn it into a flashable firmware!
Post a copy of your original firmware dump and I will make it flashable for you. That will also tell us if your drive is really an NS50 drive.
PS. I just spotted in one of your later posts your "LG BH16NS40 i have.bin file for it with Original 1.03 Firmware" statement. Since I think that the newest NS50 firmware is v1.02, that might suggest that your drive is a standard BH16NS40 (not the NS50 SVC version). In that case you will have to flash it back with a standard BH16NS40 firmware such as 1.03-A0 or better still the 1.03-C0 firmware (latest one). Post your dump and that will clarify things. Once I know what drive you have, I'll post the correct *.bin firmware for you, which you can flash using the same unlocked flasher you used the first time around.