Here's a little trick that will save you some major headaches. When you curl up on the couch to watch your favorite show, the last thing you want is a remote control with dead batteries. But don’t get up just yet. Use your smartphone to see if you actually need to replace them.
Testing this is simple. Open your phone’s camera app and switch the camera to the front-facing view. Next, point your remote control at the lens and push one of the buttons. Cellphone cameras are extremely sensitive to different types of light, including infrared.
If your remote is working, you’ll see a flickering light show up in your camera’s viewfinder. If it’s not, you’ll see nothing. And if your battery is low, the light will be extremely dim.