iPhone 6 rear camera and flash not working

Is your rear camera plugged in? It is possible that it got unplugged by accident.

"I had similar issues once with an iPad and lucky me I fixed the issue by restoring the unit. I'd try that before anything else. The other solution would be to re-open the device and make sure you didn't unplug the camera flex cable by accident when you swapped the display assembly.

-Bruno"

Here is the final solution for (Black Screen Camera),

"I also share 1 issues

We conducted replace one camera and obtained successful results

camera has become active again .

camera and flash but separate but work together,

if the camera is damaged or broken camera flash not active .

just replace cameras or lights , the problem Plash will be resolved .

no problem"

If your camera was broken, a new rear camera may fix it. If your camera is not broken it's likely a problem with the power button flex. Another possibility is a logic board or software issue, but I've rarely seen that.