Use a digital camera to test your Apple Remote
In Troubleshooting the Apple Remote - Apple Support is this tip
Use a digital camera to test your Apple Remote
basically if you point the apple remote at the camera you should see the remote beam in the image.
Using the iSight camera and FaceTime point the remote at the iSight camera and press the remote button. You should see the remote light in the image in the screen.
If you do that and do not see the light and the battery in the remote is good then the remote is most likely dead.
Please Note
It has been reported that this does not work with all digital cameras. This seems plausible.
For the record I have personally tested this with
- Cannon 40D
- iPhone 4 (IOS 7)
- iPhone 4s (IOS 7)
- iPhone 5 (IOS 8)
- iMac iSight camera (Yosemite)
- Various Mac Book Pro's iSight camera
If you run across a digital camera that this does not work with please add a comment here or in the thread that brought you here. Thanks