Chosen Solution

Hello guys, i need help because i cant find a answer for this. So i changed a lot of iphones screens from 3gs to 6. And now when i changing the lcd for last three iphones (2x5s and one 6) had some strange promblem. When i put all back, start testing it i saw when i push screen they have some yellow/blue marks on the same second when i push it. on the corners or near the home button. Maybe somebody know the answer? It can be for bad metal frame? Because im starting to give up.

Yellow marks tend to be due to pressure, this can usually happen if the side screws in the lcd shield are over tightened, or if the frame is misaligned causing it to have to move to the lcd shield and causing pressure. Or it’s possible that it’s a low quality screen. This can also happen with refurbished screens. :-)