It would be prudent to move it to an area with lower temperature. For those who are used to seeing temperatures in Celsius, that's 60 degrees C. That sounds like an operating temperature limit rather than an expected environment.

However, what is there about a NVR that would cause failures of individual inputs? I can't answer that but it seems unlikely. I'd expect global failures such as simply not playing.

Still, it's a damn good idea to get the NVR into a reasonable temperature environment. If this installation were in the desert, nobody would entertain putting it in the attic, probably because you might think it could get up to 140 degrees there, which would eventually damage the NVR. And that's what you have now.