I am owner of 6800pro for 5 days. First 2 days my bv6800 was working perfect. i made a lot of videos and photos. On 3rd day till today rear camera is not responding at all. Shows up message "Is not possible connection with camera. Be sure that other applications do not use camera or flash light". Of course after that have made my Bv reset but nothing changed. Some times camera worked and got freezed immediately. Then i procced to hard reset. Camera worked nice and then, next time i decided to use it again the same problem appeared. Once while the button for selfie appeared, I pressed and realized that front camera works perfectly even if the rear is stacked. When i changed to rear again the same message..."....".
I am very disappointed because i like the shape of this phone, abilities that seems to have but is useless withought a good working camera...
[size=150]I must say that I tried hard with more than 3 times of reset/ hard reset/ cash cleaning etc. but nothing...[/size]

Hi there, this definitely looks like an hardware failure (camera module or its connection to the motherboard). You'll have to contact your seller to have the phone replaced/repaired under warranty.