Had same problem after sitting idle for few weeks, followed some advice from previous posts, tried plugging in Iphone charger for 5mins from nothing as soon i plugged this in I got BAT symbol. I then turned on and powered the Nexus down, I plugged back in the Nexus charger and is charging fine now and seems to be working okay. However I am a little worried after reading these posts of how long this may last before happening again