shutter button not releasing - 5d mk3

[Sparry]

I'm presuming this is some kind of internal issue but hoping someone has a fix i've missed.

The shutter button on my 5d mk3 will not focus nor release to take a shot. It's the same in AF and MF, with multiple lens. Also the same if shutter release is assigned to another button. Nor does the AF work, not a twitch.

Both LV and video work fine, in MF and in AF, with the shutter button releasing and images taken. I've looked at every setting i can think of and reset all camera settings.

[deebatman316]

What happens if you press the AF-ON button. Will the lens focus then or will it not. If it does BBF maybe setup removing the AF Start button from the shutter button. Is this camera new to you. If the picture is NOT in focus and the camera is set to One Shot the camera will not take a picture unless its in focus. Does the camera report a busy message or any kind of error code.