You cannot sign a ROM correctly, as you are not Samsung and do not have their official signing keys. We use a custom recovery to circumvent key checking, so ROMs do not need to be signed.
Typically Modems for different phones don't work, as they are designed per phone. You could try out different modems, but you would have to be proficient with Odin, as flashing the wrong modem will soft brick you.
Thanks sduvick for the reply and just to clarify it wont completely brick the phone its just a soft brick and i reflash with odin if it loops ? and thanks again
Last edited: