iPhone 5S 更换 前置摄像头 需要注意那些问题?
Front camera is broken, needs to be replaced, what issues need attention?
You need to make sure first to turn off the phone.
Then unplug the battery.
Then disconnect the screen, and replace the front cam assembly.
Then put back screen, and finally the battery and test.
Here's the link to the replacement guide in case you need it.
But history is important, as in what happened to cause this, if you know? Such as a bad drop, or screen replacement? Or liquid damage? Different approach may be needed in case of the latter.