January 6, 2017 at 5:37 pm #28317
This seems to be a hardware issue.
The green LED should light when your battery is charging through the USB cable, and should be off once the charge is complete.
It seems your battery is not charging (Green LED always off) and this explains why it works only when the cable is connected.
Could you please check with your retailer / distributor for an exchange of this faulty unit ?