Well there is really only so much you can test, but lets give them a go.
- I take it you've turned the camera off and on a few times with no difference.
- Have you tried unmounting the lens and remounting it?
- I take it your batteries are fully charged? Might want to throw them back in the charger to make sure.
- You can try updating the firmware, but if it worked before, then I don't see this solving the issue.
Hopefully one of those helps,
Bob