Chosen Solution
So I have a customer come in asking if I have heard about this issue before. she has changed screen from a competitor and when she takes a selfie using the flash the phone turns off and you have to hold lock + homebutton to get it to turn on again, has anyone heard of this problem and is it a bad screen or is something else broken?
It’s the battery. When it can’t provide the high amount of power output from flash the phone will auto reboot itself. You may see that while plugged into charger or near fully charged it does not occur. You’ll need to get the battery replaced to fix this problem. iPhone 6s Battery Replacement iPhone 6s Battery
I would try another screen as some repair centres buy fully assembled screens and just swap home button I.D. It might be a defect cheap part on the screen instead of them swapping the genuine parts over to the new screen
either or all: check the battery - settings app -> battery — under battery health -> Peak performance capability - it should say that battery is supporting normal peak performance. If not — a battery needs replacement.some short inside or water damage and thus corrosion or some in-between so that if power usage exceeds the base levels - the battery does not cope and / or short occures and the system shuts down.loose connector The phone may need to be opened to evaluate 2. and 3.
