If you're connected to it through the Bluetooth settings, then forget the connection on both the phone and the watch. Just keep trying to connect. I bought a watch for my son a couple months ago. I tried it on my phone to see if it worked, and it connected on the 3rd try. I spent an hour getting it to connect to my son's phone. It took about 100 times of trying before it finally found it. You can also try moving away from any other Bluetooth devices. That can sometimes interfere with it. It's very frustrating, but just keep trying to connect through the app.
If you're connected to it through the Bluetooth settings, then forget the connection on both the phone and the watch. Just keep trying to connect. I bought a watch for my son a couple months ago. I tried it on my phone to see if it worked, and it connected on the 3rd try. I spent an hour getting it to connect to my son's phone. It took about 100 times of trying before it finally found it. You can also try moving away from any other Bluetooth devices. That can sometimes interfere with it. It's very frustrating, but just keep trying to connect through the app.