Strange screen issue with IPhone 4 32GB

[iMore Question]

So, I am new here, yesterday I got an used IP4 32GB. Everything is fine, everthing except the screen... It is flickering, changing color and has horizontal lines all over it. It looks exact like this: youtube.com/watch?v=_gE3JgdE5B0

So, I have already checked the connection of parts, everthing is fine. I suspect it to be LCD failure and it needs a replacement, but I am not 100% sure. What do You think? Should i buy a screen replacement? Or is it CPU/GPU related?

 

[pkcable]

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I made your video easier for people to watch

Why are we going to so much trouble for an iPhone 4? It has very little value at this point! Why not just get either a new phone on payments OR a newer used phone? Such as an iPhone 5S or 5C etc?