Hello Guys,
The camera of a friends S4 (mini) doesn't work. The mobile has a display damage 1 month ago. But he still could use the camera. But it seems not to work since a week. He just told me that if he try to cam with Viber with family someone else, the cam shows just a blackscreen. I tried to reinstall Viber, because he told me that he could skype with cam without any problems (today). As I opened the Camera App, I get a error: Warning: Camera error. And the app closed. If I restart S4, the cam suddenly works and after 5 minutes the error appears again. Can someone help me/him please?

Thank you