I had the same problem with one of my iphone 5 lcd's where the touch screen was working totally fine when it was lifted about a cm from the frame but after totaly installing ,it acts crazy and gives random touch point,they call it ghost touch
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Investigate the ribben cable for naked cupper and use elec. tape on that area
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Or use sth on top of connector for making sure they are in place
I had the same problem with one of my iphone 5 lcd's where the touch screen was working totally fine when it was lifted about a cm from the frame but after totaly installing ,it acts crazy and gives random touch point,they call it ghost touch