Camera Update Firmware error topic

Wondering if there is a common fault with the S4 camera. When trying to use it, it gives me a firmware updating error. The Rear camera never starts up. The front one is fine. I have recently tried to replace the camera with another one and when I turned on the phone it gave me the firmware updating prompt even before I started any Camera App. Is this an actual Firmware issue or is the Main board kaput?
Thanks for any advice