I finally got my phone replaced, and it is week 38 with the panel that is supposedly not good. How can I tell, if I'm affected by negative black? I can tell the screen is not as good ,but old phone was 5 series, so I can live with regular 7 series quality, but I don't want negative black. Is there an easy test to detect it ? I don't want to miss it, and be too late to return. Thanks for the help!