My Apple TV remote will not charge. What to do?

Do you have the Siri remote?

Try to charge it as described in these instructions: Charge your Siri Remote - Apple Support

Charge by connecting to a power adapter in an AC socket, or directly to a computer, using the bundled Lightning-to-USB cable. The Siri Remote takes about three hours to fully charge. The are no indicators on the remote that it is charging, but you can monitor the battery charge level on screen.