LCD stays dark after replacement at cold start, swap shows image
Hello, we are a professional repair company located in switzerland with 17 branches nationwide. we recently noticed something very strange with display replacements at the iphone 6 Plus where we just can't get to the bottom of the issue. the situation is as follows: An employee of ours used a iphone 6 plus replacement screen and mounted it on an iphone 6 plus that had a broken screen. after unhooking the battery he mounted the replacement screen, attached the vbattery again, tried to start, and nothing happened. so trying to figure out what was wrong, he disconnected the battery again, removed the replacement screen, attached the old screen that had a broken glas, reconnected the battery, tried to boot and voila there is the apple logo again. He then checked the same replacement displays with three other phones and the lcd never lit up. so assuming the display was defective he sent it do headquarters, where we hooked it up to our screen tester, there the lcd showed up just fine. we returned the apparently functioning screen back to him where he tried to use it with another customers phone. he then noticed that if he attaches this replacement screen to an iphone if it booted up with a damaged screen and then swapped it "hot" while the battery was still connected to the logic board, the lcd would show a picture and would work properly. if he then would turn of the power and reboot the display would not show any image again.
however if he would use old broken screens on the same phone he could restart them every time with the lcd showing an image, but he could only get the replacement screen to work if we would boot with an original screen and then swap it. does anyone have any explanation why that is?
On a sidenote, we take great care in sourcing our replacement parts in china, we visit twice a year, inspect the sellers factories, and are quite picky with quality. our return rate so far has been below 1.5%. since we are so focused on quality we want to get to the bottom of it, since we cannot figure out why the screen would only work when swapping it on a turned on phone ( which basically is against all the rules in the guidebook, since the risk of damaging the logicboard is there).
any input from you guys is greatly appreciated! thank you
Well the thing is, it is this particular repair guy that is having issues with our screens, all the other repair shops are not experiencing these issues. i am still unable to tell, what they are doing different with regards to the procedure in comparison to the others. Do you have any experience regarding the repair procedure that deems screens unusable due to an error some repairshops make? thank you for the answer... unfortunately being swiss does not help us with this one :-)