Unpair and re-pair a Siri Remote (2nd generation or later): Press and hold the Back and Volume Up buttons for 5 seconds
Wait for the status light to flash rapidly, then press and hold the Back and Volume Up buttons again for 5 seconds
Follow the on-screen instructions on your Apple TV to complete pairing
Reset a non-Siri Apple TV remote: Remove the batteries, wait 30 seconds, reinstall the batteries
Unpair and re-pair Apple TV Remote (A1294/A1427/A1513/A1521) using the Apple TV: Settings → Remotes and Devices → Bluetooth → select the remote → Forget Device, then pair again
Reset Apple TV (if remote pairing won’t complete): Settings → System → Restart
Factory reset Apple TV (if needed): Settings → System → Reset → Reset and Update
After reset, pair the remote again using the on-screen prompts