Chosen Solution
Hi all I recently gave a fully working iphone 6 to a family member, the only issue being a small hairline crack on the screen, other than this the phone was fully working and the image and touch was not affected by the small crack. They took the phone away and everything was fine, there was no mention of wanting to replace the screen, otherwise I’d have offered to do that. Only a few days later I get a message saying they’ve tried to replace the screen and now the phone won’t switch on. After testing the device, I can confirm it is powering on and booting up. It is recognised by itunes. The issue is no image and no backlight, it’s not just a mis-diagnosed backlight issue. The replacement screen is working fine when tested with a known good board. I have also tried other known good screens and there is still no image and no backlight. I have checked and compared diode readings for all connections on the display connector, they are all reading fine. I have also checked there isn’t any long screw damage. I’ve checked the voltage readings on the display connector. I am getting 1.8v on PP1V8_LCM_CONN, i am also getting 5.7v on PP5V7_LCM_AVDDH & PN5V7_LCM_AVDDN. I’ve also checked there is 1.8v showing on the 2 I2C lines. I wasn’t getting the voltages relating to backlight, but I traced this back to the backlight driver which I replaced and I now have backlight voltages. As a wild guess I have replaced U1501 (Chestnut) display PMU, but unfortunatley this hasn’t resolved the problem. I have also checked the chestnut enable and reset lines, I can confirm chestnut is being enabled and working and the phone is detecting there is a screen connected. I can see without the screen connected I do not get the 5.7v and with the screen connected the 5.7v appears. The display connector itself looks absolutely fine and I’d prefer not to change it, as I can’t see any issue with it. Any ideas? It’s probably not worth the effort for the age of the phone but I’d just like to know what the issue is, this will help my knowledge when trying to diagnose similar issues on other devices. Thanks all and appreciate your time for reading this.
That screw hole wouldn’t affect image. And the middle screw hole is your PP1V8_LCM_CONN which you have. So the connector will be the only other thing to try.
