Hey Karen2015 -
Here’s a basic troubleshooting tutorial. It walks you through the process in a stepwise manner & provides one of the specific details you were looking for (eg, 5sec hold). Depending on whether you have an Apple remote or Siri remote, the button combo is a little different.
My 2¢ fwiw: Whenever I first see evidence of an efailure to communicate, I prefer to restart/reset everybody before proceeding. Just a basic power cycle reboot.
Following that premise:
-If you see the option to forget device for your remote, then go for it - it may or may not help but shouldn’t hurt.
-Same principle applies to restarting your Apple TV.
-And I would go ahead & restart my remote too (scroll to the bottom of the page I linked above).
And then proceed with pairing.
Good luck. 🙂