So i had a old iphone 4 laying around with a broken screen and battery problems. I replaced the screen and battery and today and it was working great.. untill I put the screen to sleep.
Thats the phone.
I watched your video and I understand your concern.
Article: TS2802 iPhone: Hardware troubleshooting
It looks like a hardware issue from what you have already done and what the video shows. Try the display section of this article.
Hope this helps,
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