D600 random “err” messages and question

I’m getting random “err” messages and the camera froze, after pressing the shutter button repeatedly it works again. It’s not the memory card as I have tried more than one (all of them approved by Nikon).

I just reset the camera and fully recharged the battery and I’ll keep testing before contacting Nikon service. But now I see that if I use the 2 “Format red” buttons to format the memory card nothing happens, the pictures are still in the card so I guess this function is not working or is it different as when formatting through the menu?

Thanks in advance,

Ed.