This is an older unit passed on to me.
What is the exact model?
Identify your Apple TV model - Apple Support
Find your Apple TV model number - Apple Support
Missing the remote, so bought a new one, and it looks like it paired,
The remote should match the box model for compatibility.
- “Legacy” Apple TV (1st to 3rd generation) [A1218, A1378, A1427, A1469]: use Apple Remote (aluminum) “1294”.
- Apple TV (4th generation or 4K) [A1625, A1842, A2169, A2737, A2843]: use Siri Remote “A1513”, “A1962”, “A2540”, or “A2854”.
Apple TV remotes and their compatibility - Apple Support
Replacement remotes should be paired (modern) or linked (legacy) to the box, by using a special button combination.
but only screen that comes on is a notice of using Airplay from another ios devlce and 2 other comments.
That description seems to match the “Conference Room Display”. That can normally be exited by using the Menu button or Back button on the remote. You can turn off that feature in Settings﹥AirPlay﹥…
In some cases, Conference Room Display could be locked with a PIN number through Restriction Settings. If you don’t know that code, then a device reset would remove it.
Or in case the unit was once used corporately or in a school setting, then it might be locked to Conference Room Display through a loaded device profile. That would stay even after a reset — it can only be removed by the original system administrator.