My rear-view camera (shown in rear-view mirror) has become blurry. I've cleaned the camera lens, but no improvement. Is the camera difficult to replace?

Most of the time the screen is black, purchased my SRX used.

Got a used 2012 cadillac SRX yesterday.
After driving of 5 minutes, I see some heat in the front grill, and also I feel engine hot.
I don't see any peculiar indicators on other than rear axle service. Is that engine heat normal, or how hot should an engine be after driving. I see coolant to be half full. So not sure if any major problem in gasket. Please advise. It's under warranty and hope they service on what is required.