My Lumix GH4 camera will not turn on.

I have three Panasonic batteries for this camera, while checking them before a shoot only the second one worked. The camera turned on and said the battery had 2/3 bars. Okay yeah, checked the third and once again no life. I checked the second one again and... Nothing. The camera didn't turn on. I've spent about 24 hours charging all three batteries so they are fully charged and still nothing. I've carefully cleaned the metal bits (technical term I know) on the batteries and the prongs inside the camera and still nothing.

Side note: I noticed that on the batteries there's four metal bits, but in the camera there's only three prongs. But there's marks on all four on the batteries like there should be four? So am I missing a piece? It doesn't look like anything been snapped off, there's three prongs and then a screw inside the battery compartment.

I've read though my manuals and tried to look in to it online but I can't find any where to see what the inside compartment looks like.

I am totally lost. I really need my camera!