Elsa, is this the in-camera battery, or the battery in the grip? Just wondering if a bad connection between grip and body could cause something like this?
Also, there are a couple of other settings in the Setup menu which I would make sure are turned off, just in case.
Such as making sure Bluetooth is not set to "send while off" and Eye-fi is set to disable.
I believe that airplane mode should take care of these, but just in case?