Chosen Solution
Hello - Okay, weird one here.. I fix iPhones frequently for people (40+) and havent ran into this as of yet. After replacing a cracked screen, the front camera is not working if the flex digitizer, lcd, camera shield plate is installed. If you remove it, reseat the front camera cable it works fine. Tried two different front cameras!! WEIRD! Thanks for your input…
It sounds like something is grounding out somewhere. Try putting a small square of electrical tape on the camera before you put the speaker and camera shield back on. Maybe cover the sides of the camera as well. The tape shouldnt be too thick as to cause fitment issues.