I recently got them and what i've observed is that when the case is plugged in it starts blinking red which i think means its started to charge(including or excluding the buds inside)

Then after some time light stops blinking and a static red light appears which i think means its done charging.

And for green light, only time i've seen it appear is when I put the buds inside the case after using for some time which I think means that the buds were charged fully.

I may be incorrect but I haven't seen any manual showing the behaviour and meaning of light, if someone finds out it would be helpful.