If your Roku Remote Is Not Working, you are not alone. Many people have experienced issues with their remotes and there’s a variety of potential causes. Fortunately, troubleshooting the problem doesn't require a lot of technical expertise.
The first step in resolving your issue is to determine whether or not it is related to the actual remote or something else, such as a connection issue. If your Roku device powers on without using the remote, you may need to reset or replace it. However, if you cannot power on the device at all, you may need to check that all connections are securely attached and power cords are plugged into outlets correctly.
If these steps don’t help resolve the problem, try replacing the batteries in your Roku remote and ensure they're installed properly.
Source: Remote For Roku Not Working