Airfun air case lights

I am not sure if my earfun air case is charging or not - this is not helped by my confusion of what lights I should expect when it is charging! The manual says the blinking red light indicates a very low battery (less than 10%), but when I put the case onto charge, I get a slow blinking red light. Does this suggest the battery is low, or that it is charging?! And what should the light be when the case is fully charged but still plugged in? I am not confident my case is charging but at the moment I am unsure how to check or how to tell.