Is there a notch on the Nikon D800 battery grip connector?

About 2 pins from the start, which is on the side towards the middle of the camera, and the notch is about 4 pins wide? It would also be on the D800E.

Have you followed the instructions when attaching the Nikon MB-D12 battery grip?

You will see that there are many more than just 2 or 4 pins.

I have linked you to the user manual