The battery thing is rare... I have five batteries and all are working perfectly... so that's really unfortunate.
I have received compass errors taking off of my deck that has metal screws in it... so check the surface you are taking off from an ensure you don't have any metals that could interfere with the compass... then do a compass calibration.
Lastly - try this product - Strong Arm reinforcement plate sure you shouldn't need it... but it's better than sending the bird back...