Apple recommends to try restarting just the remote, in order to attempt to bring back volume control functions. Use the indicated button combination to do so.
If the volume buttons on your Apple TV remote aren't working - Apple Support
The battery should last months. Charging every other day shouldn’t be needed; the charge level isn’t the issue most of the time. It is functional to about 2% charge. Charging should bring the charge level back to ~84% in about an hour, or to 100% in 2.5–3 hours. You may check the charge level in Settings.
If the battery itself is the cause of issues, then consider contacting Apple about Battery Service.