Finally unlocked it.
Heres the tip. best to download the tutorial for XS++ from Akshay's Webspace and the files are also there (note firmware does not have to be the same as that orignally on the phone but the mian and fs have to be the same along with the cus pack).
Did not realise the main flash was mbn and fs was the fbn, but since the tutorial it all makes sense and its plane sailing afterwards.