Hi Mohammed
I used the advice above
Attaching the digitiser only and having powered down, powered up, swiped to unlock and then used my pass code by guessing the location of the numbers. Having powered up and unlocked the phone was recognised by my laptop so I updated the iOS to the current one. This took ages but once done I then powered down, reconnected the screen to the mother board and powered up the phone. To my amazement and joy the screen lit up so that I could swipe and unlock.
Hence my post
Good luck. If your phone is not knackered and needs the most current iOS it will work with a good deal of time and patience.