01-07-2017 12:59 PM
This is easy to validate visually.
Set the camera to Manual exposure mode. Dial in an exposure time (shutter speed) of 1 second.
Remove the lens (so you can see into the front of the body.
Take an exposure while looking into the front of the camera.
You should visually see the reflex mirror swing up (snap up -- because it happens very quickly) and the shutter (a series of overlaping "blades" - sort of like a set of blinds) should open and close. There are technically two sets of these and it will all happen so fast that it'll probably look as if the shutter just disappeared. But the main thing is that you want to verify that the reflex mirrors were able to swing clear and the shutter blades also completely opened for the shot.
Here's a video explaining what you should see -- but the video is in extreme slow motion (this was done with an original 7D, not the Mk II, but the shutters are DSLRs all work similarly.)
The image you would have just taken will just appear to be a white frame (since there is no lens on the camera it can't focus anything) but the camera will still record the image and it should not be black.
If all that works, then the problem is likely something else. But if any of that doesn't work, the camera body should be swapped since it's a brand new camera.