Update regarding this problem of a blank screen when retrofit .
The ACM , FCIM and APIM module were all from different vehicle recheck the wiring loom all fine.
Download 3.4 update to a usb plug it in screen was still blank for about 60 sec then got a white mustang upload screen which is the first time I’ve seen that working with these module. Download took about 50 mins and now every is working perfectly so many thanks for all your help.
Gone from single Din FM only pieces of rubbish to this nav and dab.