Red stripes showing on display when overheating

Guys since three weeks ago i’m experiencing problem with display. When i use multiple apps phones starts to overheat and red stripes appear on the screen. Does anyone know what might be causing this problem and how to fix it. Phone is six months old, before this i didn’t had any problems. I’ll post two photos of display.

Six months old…warranty ofcourse!

Phone was ordered from China through aliexpress, I contacted the seller, he gave me one address to send the phone, than he gave me another one…honestly i’m affraid to send it there, i feer it might be “lost” in the sending or recieving part…i would just like to know what’s the problem, is it a screen or a motherboard…

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