Chosen Solution

Hi! I replaced the screen for iPhone 6s plus. Now the cameras arent working. If I havent plugged the front camera connection in, then the both cameras are black. If I disconnect the front camera the rear camera starts working fine.

If rear cam works after disconnecting front cam then you’ll need to replace the front camera assembly. Most likely due to a torn flex. iPhone 6s Plus FaceTime Camera and Sensor Assembly Replacement iPhone 6s Plus Front Camera and Sensor Cable

Most likely you damaged the front camera assembly during the repair. This can be a hard piece to remove if you don’t have a lot of experience. Did you just pull it off the old screen? In the future, a little heat will help loosen the adhesive.