I don't personally have any information for you, but I ran across an article on nextpit.com that claims to know how to fix the Camera Failed issue. They say it's strictly a software issue, that there's nothing wrong with the phone itself.
# Restart the phone.
# If that doesn't work, go to the applications manager under settings and clear the data and cache for the camera app.
# Otherwise, put the phone in recovery mode and wipe the cache partition.
# If it's still not fixed, go into the display settings and turn off Smart Stay. That may fix it in the short term, but according to Samsung the long term fix is to update your phone's software, as it's apparently a known issue that's been fixed in a later revision.
You can get details on each step at the original article here.
[link|https://www.nextpit.com/how-to-fix-camera-failed-samsung-galaxy#galaxy-s7|How to fix 'camera failed' on Samsung Galaxy smartphones|new_window=true]
Hope this helps!