I bought a brand new 5DM4 from Canon online about a week ago. Getting used to all the controls and going through the menu, the camera is turning off after a few seconds. I have a Canon battery in it and the display shows two bars. Looking at the manual I have between 49-20% charge. The only way to turn on is to turn the dial to off and then on. After turning off a few times, it completely stopped turning on. I used a third-party battery (Neewer) with 100% charge, and the camera stays on - no issues.
Is the battery defective? Or the camera getting incorrect battery reading? Or some other issue with the camera itself?