Why is there no audio or video on Input 1 or channel 3 for my N64?

I have a Nintendo 64 that is connected to my old box TV by an AV cable and a power cord. My first N64 worked on this television, but it finally died after 26 years, so I bought another one. I couldn’t figure out how to connect the cord with the cable-like ends, so I bought the AV cord. Whenever I power the system on, its red light turns on, but I only get a flicker on the screen on Input 1 and literally nothing for channel 3. I bought a third N64 and nothing has changed. How do I fix this?