Welcome to the Roku Community and thanks for posting regarding your Roku Smart Home Doorbell not charging.
Have you already tried using a different cable and charger. In addition, make sure you are plugging it all the way in to ensure proper charging.
If you are still experiencing an issue, we would recommend trying to perform a restart on the Smart Home Device. Lastly, if you are still unable to resolve the issue, you can try performing a factory reset.
Please keep us posted what you find out and we will be more than happy to continue assisting if you need further help. We look forward to hearing back from you.