My mavic is useless cause of this "battery authentication failed" problem. Drone was working fine, got a "cannot take off" message on controller and been down since. I bought a new battery and still get the same message. I have been trying to go back to a earlier firmware and have had nothing but trouble either my aircraft wont connect or installation fails. Im at a loss. Could it be both batteries are bad? If anyone can steer me in the right direction on this it would be greatly appreciated.  

Hi cyberflyer, I'm sorry for that case happened. Please contact our support team via http://www.dji.com/support to open a case and send it in for a diagnosis. We'll do our best to help this out.

I bought a Phantom4 with 3 batteries >1 year ago and have been having the same problem, most of the time, with only 1 battery. I have been able to fly with it a few times for reasons unknown. I finally found a temporary solution, but do not understand why it worked. It might work for your Mavic Pro. I connected my Phantom4 with the problematic battery to the assistant app. My firmware was already up to date and therefore I did not do any updates, nor did any reset to factory defaults. I then disconnected it from my laptop, connected with my controller and did not get the message. I then restarted the drone and did not have the message at that time either. I am assuming that the "battery authentication failed" message will pop up again when it is least expected and inconvenient, as it has in the past.

Sounds like a bad firmware misreading the battery details, or the connections on the battery connector are damaged or dirty.
If assistant is letting you down then try drone-hacks tool, it has a much better system for flashing firmware

Did you got this problem resolved?

Do ya have the FW leaved on SD card in card slot? If yes then try to update the battery´s FW for sure. It takes around a minute of time after powering on the AC and RC.

My battery did this out of the blue been using it I don't know how many times it's been charged but I haven't done anything to firmware updated anything and it just appeared The only battery out of five that I've had for a while help!