Apple 4K Remote
My Apple 4k remote will not take a charge, any thoughts?
Did you charge as described, getting energy from a computer or wall charger (power adapter), using the supplied Lightning-to-USB cable?
Did you monitor the charge level (%) in Settings, during charging?
Charge your Siri Remote - Apple Support
Charging could take up to 3 hours, according to the documents. But the remote is functional during charging.
For optimal longevity of the battery, you should charge when you get the 20% warning.