Hi there! I see you're having trouble with the Instant Heart Rate app's light not turning on. Just to clarify, you mean the light that is supposed to come on when you measure your heart rate with the app on your iPhone, right? The green or red light that the app uses to detect your pulse?

Could you tell me a bit more about what happens when you try to measure your heart rate? For example, does the app open fine, but no light activates when you place your finger on the camera? Or does the app give any error messages? Also, have you tried any troubleshooting steps already?

This info will help me guide you better!

The app opens fine, but no light activates when I place my finger on the camera. The app gives the error message “no finger.”

Thanks for the details! Since the app opens fine but the light doesn't activate and you see a "no finger" error, it suggests the app isn't detecting your finger properly on the camera with the LED light.

Let's try a few steps to resolve this on your iPhone running iOS 18.6:

1. Check Camera Permission:
The app needs permission to use your phone’s camera and light. Go to Settings > Privacy > Camera and make sure Instant Heart Rate is allowed access.

2. Clean the Camera and Flash Area:
Sometimes, dirt or smudges on the camera lens or flash can interfere with the light activating. Use a soft, lint-free cloth to clean the camera area gently.

3. Restart the App and Phone:
Close the app completely (swipe up from the bottom and swipe the app away), then reopen it. If the problem persists, try restarting your iPhone to refresh the system.

4. Update the App:
Make sure you have the latest version of the Instant Heart Rate app installed from the App Store, as updates often fix bugs.

5. Check for iOS Updates:
Occasionally, system updates improve hardware and sensor compatibility. Go to Settings > General > Software Update to confirm you're on the latest iOS 18.6 version available.

6. Try a Different Environment:
Low light or harsh sunlight might affect sensor detection. Try measuring your heart rate in moderate, indirect light conditions.

If after these steps the light still does not activate and the error continues, there could be a deeper issue such as a software conflict or device sensor problem.

If you want, I can guide you on further advanced troubleshooting or assist in contacting support for help. How does that sound? Would you like to try these steps now?