IPhone7 plus back camera not working (black screen)

Hi

I am using Iphone 7 Plus ( Black) since 2016, recently since two weeks I am facing issue with Back camera. Its not at all working while in Photo/Video/Portrait mode. Its working fine when I switch to Slow Motion or Pano mode.

Front camera working fine. When I check with Apple support, they suggested to do Factory reset by expecting there should be some issue with Data I have in phone. But no luck after doing factory reset and set as new Iphone.

No other support from Apple on this issue.