Why does my device that connects to Bluetooth devices such as a watch, but its screen doesn’t light up?

Finally, check if any third-party apps might be interfering with the Bluetooth functionality:
1. Review recently installed apps on your main device.
2. Consider apps that have permission to control Bluetooth settings.
3. Disable or uninstall recently installed apps one by one.
4. After removing each app, try connecting your Bluetooth devices to see if the problem is resolved.

It sounds like there could be multiple reasons for your issue. Let’s start with some fundamental checks: 1. Software Update: Make sure your main device’s operating system and firmware are up-to-date. Sometimes, outdated software can cause compatibility issues with Bluetooth devices. 2. Bluetooth Settings: Ensure that Bluetooth is enabled. Simply toggling the Bluetooth setting off and then on again can sometimes resolve minor connectivity issues. 3. Battery Check: Verify that your main device’s battery is not critically low. Low battery power can sometimes cause the screen to stay off while trying to conserve energy. 4. Restart Devices: Restart both your main device and the Bluetooth peripherals. This can reset any temporary glitches that might be causing the problem. 5. Compatibility: Check if your Bluetooth devices are compatible with the main device. Refer to the manufacturers’ websites for compatibility lists. 6. Reset Bluetooth Settings: On your main device, go to Bluetooth settings and unpair all previously connected devices, then try pairing them again. 7. Screen Timeout Settings: Make sure the screen timeout settings are not configured to turn off the screen immediately when not in use. Adjusting this setting might help in keeping the screen on when a Bluetooth device is connected.

It might be a hardware issue. I encountered a similar problem, and it ended up being a malfunction in the display’s backlight. Here are a few things you can try to diagnose if you suspect a hardware issue:
1. Try connecting a different Bluetooth device like headphones or a speaker. If the screen still doesn’t light up, it points towards the main device being the problem.
2. Connect your main device to a power source. Sometimes, the main device screen might not light up if it’s not receiving power properly.
3. If you have access, try connecting your main device to an external display to see if it works. This might help identify if the screen itself is the issue.
4. You may need to visit a certified technician to check for any potential hardware damage, especially if your main device has been exposed to physical impacts or moisture.

Sometimes, the issue might be with the Bluetooth stack of your main device. A corrupted Bluetooth stack can lead to unpredictable behavior. Here’s how you can reset it:
1. On your main device, go to Settings.
2. Find the System or General Management section.
3. Look for options like ‘Reset’ or ‘Reset Settings’.
4. Choose Reset Network Settings or Reset Bluetooth. Note that this will remove all saved Wi-Fi networks and paired devices.
5. After the reset is complete, pair your Bluetooth watch again and see if the screen lights up as it should.

If all else fails, it might be best to perform a factory reset on your main device. Be sure to back up all important data before doing so:
1. Open settings and find the System menu.
2. Navigate to Reset options.
3. Select Erase all data (factory reset).
4. Confirm and proceed. This will erase all data and settings and return your device to its original state.
5. Once the reset is complete, set up your device again, and try connecting your Bluetooth watch.

I think this could be related to settings in the main device that handle notifications or display settings. Here’s a method to address it:
1. Check the notification settings on your main device. Sometimes, notifications can turn on the screen if set that way.
2. Look at the Do Not Disturb settings; ensure they aren’t preventing the screen from waking up when connected to Bluetooth devices.
3. Check any app-specific permissions, especially apps that handle the Bluetooth connections. Make sure these apps are allowed to wake the screen.
4. If there’s a specific app for managing the Bluetooth watch, delve into its settings and see if there are particular configurations for screen wake behavior.

Once, I found out that the Bluetooth connection issue was due to interference from other devices. Bluetooth operates in the 2.4 GHz spectrum which is also used by many other devices:
1. Remove or turn off other electronic devices that might be causing interference like microwaves, cordless phones, or other Bluetooth gadgets temporarily.
2. Keep your main device and Bluetooth watch closer to each other during the initial connection.
3. After ensuring there’s minimal interference, check if the issue with the screen persists.

I had a similar issue, and it turned out to be related to the power settings on my device. Here’s what worked for me:
1. Go to the settings menu on your main device.
2. Find the power management or battery settings.
3. Look for an option that might be labeled ‘Battery Saver’ or something similar.
4. If enabled, disable the battery saver mode. Sometimes, battery saver settings can restrict background processes and screen activities.
5. After doing this, perform a restart of your main device and then try connecting to your Bluetooth watch again.

In some instances, the Bluetooth protocol version mismatch can cause connection problems:
1. Check the Bluetooth version of your main device and your watch.
2. Ensure both devices support similar Bluetooth versions or at least compatible ones.
3. Consult both devices’ manuals or online resources for information on supported Bluetooth versions.
4. If there’s a mismatch, consult with the manufacturers for updates or firmware that can ensure compatibility.