Hi there. I received a new battery directly from DJI. When I plug it into the phantom 2, and power up, all lights flash, then just two sat on solid red. Rotors won't fire up, copter is non responsive to ground station. The other battery that came with the kit works totally fine!

Suggestions?

Cheers

For clarification, do you mean there are only two lights on the battery that are lit up?  

If it is the two center LED's that is usually is an indication for a failed battery firmware update.  Did you check the assistant software to see what indications it has about battery status?

Are you able to charge the battery?  If not you may be able to "reboot" the battery by turning it on (OUTSIDE OF THE PHANTOM!) by holding the button for 5-10 seconds at which time it resets the LEDs.  Or, while it is plugged into the charger, turn the battery on (press once, then press and hold)  It should take a charge after that.

If none of that works you need to email DJI within a week of it's delivery if you want to get an RMA and return it.