Chosen Solution
Although it seems to be quite rare, this iphones backlight sometimes doesn’t turn on or even stops working while using the phone. A few momenta after it starts working again or if doesn’t, it will come on with a restart. I took it apart, but nothing seemed to be damaged. The phones camera also turned black on me with the flash not working (saying it needed to cool down). At this point I am out of ideas, because it doesn’t seem to be consistent. Thanks for any help.
You definitely have some logic board damage. You have two issues here, the backlight and the flash/camera. If you are getting a message indicating that there is excess heat, that’s a sign you have a short somewhere that is causing localized heat. This can probably be easily resolved but it will require that you have it looked at by a repair shop that does micro-soldering repairs. The backlight issue can be caused by a screen repair gone wrong, for example, not disconnecting the battery prior to removing and installing the screen or it by a screwdriver or fingernail gone astray.
There might just be a problem with the backlight filter in the device. So, if you have the ability to test it, then test it, but if you don’t, then just bring it to a professional.
