5D Mk iii buttons no longer working

[ronbaker]

All of the buttons on my 5D Mk iii except for the shutter and top display light have stopped working.  I was shooting outside last night in light snow, temperature just below freezing.  I swapped lenses a couple of times (24-105 and 17-40) carefully.  The problems didn't start until after downloading the photo files using a card reader. From time to time, the functionality returns, and then goes away again.  Replacing the battery and resetting custom settings has not helped.  The lens has been removed for long enough that any trace moisture should have evaporated.  Swapping the lens has, on occasion, resulted in a "not communicating with lens" error.

I have not been able to find any indication on the various forums of anyone having a similar problem.  Suggestions would be appreciated.  Thanks.

[TCampbell]

Do you, by chance, happen to have a battery grip?

If so, you may want to test the camera without the grip installed.  

[ronbaker]

Thanks for your suggestion, Tim.  I do not have a grip, and I have tried switching batteries.  I have also tried with and without memory cards.  I expect to have to take it in for repair, but the store I deal with is closed today for New Year's.

[TCampbell]

In full "auto" mode, you get locked out from using some buttons, but you will get a message (e.g. "function not available in scene-intelligent auto mode", etc.)  so at least you know the camera recognized that you were pressing the button.

From what I gather... it sounds like the buttons are behaving as if you aren't even pressing them.  Perhaps a loose connection inside the camera is responsible.

This sounds like the camera will need to be serviced.