Help Making it work after the green battery pic


When it discharges all and recharge it a green battery pic appears until 100%
What to I do it next?
If I take out the cable, a black screen appears
If I leave it the cable, it shows that battery indefinitely
Few times I managed to put it in function-it will reboot. But what is the sequence of what to do?
Related question: is there an external way to reset/reboot?
I am a novice