Screen flickering

It seems like this is hardware issue with the screen connection to logic board, we have had quite a few Samsung or iPhone handsets showing similar faults with their screen in my workplace (I am working in a wee shop selling second hand technology) and screen replacement usually fixed that issue. Bare in mind that if you are using Samsung device your screen replacement might be a bit costly, depending no the model.

I would recommend popping into your nearest Carphone Warehouse store for a quick quote for repair as they will use authorized parts and service which will not void your remaining warranty.

Regards