Both cameras stopped working

I use my iPhone 6s Plus only inside, hardly outside. It has never fel, no damages whatsoever and protected by a good cover. It had the official battery replacement in Jan 2018 by the official apple dealer here in Malta. Never had any problems with it.

Obviously it is out of warrantee but even after the battery replacement all worked well as should.

Three weeks ago I had a facetime call and the front camera was not working anymore. I checked the rear camera and that worked in the camera app. So I turned of the iPhone and restarted it again, thinking it was some software (iOS) bug. Then the rear camera stopped working too, and the flashlight. Started reading on the interweb and noticed I was not the first and only one. On the Apple support site a lot of people encountered this problem, most of them where replaced by a refurbished model. That made me think that it was a hardware flaw and Apple would replace defective models. So I brought it back to the Apple dealer but as my warrantee was over the repair costs would come to €290 euro. The frustrating part is that nothing happend to the phone, it just started out of the blue and stopped working (rear camera) in my hands sitting on the couch.

I still can't believe the hardware just broke, I have a feeling it's in the software. So I did a complete clean install setup as new iPhone. That did not work. I tried most things on the internet I found on this subject, but not working for me.

Does anyone know what might have gone wrong and what options I have?