New 6D: ERR 20

Hi;

i just received my 6D, but it seem broken.

impossible to take a photo, each time i press the shutter button i get an ERR 20.

i tried a different battery, with or without lens, card, etc.

but nothing, ERR 20 all the time.

i flashed the firmware to 1.12: but no way to take a shot.

the mirror dosen't flap

any suggestion before to send it back?

thanks