I got this from an electronics mechanic recently when I saw him repair a TV remote.
Switch on your mobile phone camera and hold the remote under it with the IR emitter facing the camera. Operate the remote. If it is working, the IR light will be seen in the camera.
Switch on your mobile phone camera and hold the remote under it with the IR emitter facing the camera. Operate the remote. If it is working, the IR light will be seen in the camera.