Alright Einstein, sorry for making you loose time with these "hundreds of lines"..! I have tested this on 3 phones & they're all on marshmallow. I kept rebooting all phones, the watch, factory resetting it..
Going in BT settings, sometimes the watch appear, yet it doesn't on the app. Even though it does, i can't connect to it. So, does it means BT's dead on the watch or..? I'm about to order another, while returning this.