Thank you for letting us know about the remote battery drain issue you are experiencing.
Please perform a system restart from your Roku device. This will update your remote to the latest version. This can be done by navigating to Settings > System > System Restart. After you perform the system update, continue to use your device as normal and monitor the remote battery percentage listed under Settings > Remotes > About. Additionally, if you had moved your Roku device power source to a wall outlet to help address this problem, you may now reconnect the USB cable to your TV's USB port if preferred.
If you are unable to resolve the issue, please send me a private message with your Roku account email address, and include the serial number of the Roku device from Settings>System>About along with a summary of the issue you are experiencing. I'll be able to assist you further from there.