My Apple TV remote is not working, I replaced the battery still not working . How do I use my apple iPhone version 6 to set up remote on my iPhone

Identify your Apple TV model - Apple Support

Identify your Apple TV remote - Apple Support

Learn how to link or pair your remote again: If your Apple TV remote isn’t working - Apple Support

Regarding the Apple TV Remote app:

The Apple TV (2nd or 3rd generation) need a functional remote to set up the Apple TV Remote app.

The Apple TV (4th or 5th generation) should recognize the Apple TV Remote Control Center widget or the Apple TV Remote app, even without a remote.

For the Apple TV (2nd or 3rd generation), your options are:

• buy a replacement Apple Remote (aluminum);
• temporarily borrow an Apple Remote (aluminum) to help set up the app;
• restore the Apple TV and connect a wireless keyboard to help set up the app;
• restore the Apple TV and connect the CiderTV Mac app to help set up the app.