Step – 1 Check out the Settings to make sure you have set it up correctly, to begin with. Go to Settings >General >Accessibility. Scroll down to the Hearing section and make sure that the option “LED Flash for Alerts” is turned ON here.
Step – 2 Keep in mind that this feature only works when your iPhone is locked. (Screen has gone dark). Click on the lock button on the side of your iPhone to lock it and then give it a try.
Step – 3 Check your Do-Not-Disturb Setting. If you have it turned on, this will not work. The same goes for the Airplane mode. Sometimes these settings tend to get overridden when you accidentally press them in the Control Center. Swipe up from the bottom of the phone and make sure that the DND and the Airplane mode is appropriately set.
Step – 4 Double tap on your home Button and check if you have the camera / flash app open. If So, close the app by swiping it upward. Restart your iPhone and test your LED Flash functionality
Step – 5 In certain cases if your iPhone is overheated due to usage, the LED flash may not work. In these cases, try switching off your iPhone for a few hours and then try to test the functionality. It’s also a good idea to restart the iPhone by pressing the Home and Sleep/Wake buttons together for 10 or 15 seconds till you see the Apple Logo show up on your device. Occasionally resetting your phone this way can often help with problems.
Step – 6 Check your low power mode Setting. Switch it to OFF and then give your LED Flash feature a try. Sometimes, having the Low Power mode switched ON can impact this functionality. You can check your settings by tapping on Settings > Battery > Low Power mode