I have had my Phantom 4 Pro 2.0 for 1 year and have no complaints about the drone itself.
I purchased 3 long-life batteries (5870 mAh). One of the batteries frequently gives me the "Battery Authentication Failed" error.  This has been occurring for several months, and I unfortunately wasted a lot of time trying to figure out a fix, rather than have it addressed with DJI when it first occurred. Considering my purchase was more than 1 year ago, I am assuming that I will get no support for this defective piece of equipment. I have read through multiple forums and have done everything that is recommended, including using the Assistant app and doing a factory reset. The error is frequent enough that the battery is not usable. Looking at my log files, I found that the battery has not actually been used very much. Occasionally I will start the drone and not get the error, but the error message will usually pop up within a few minutes. This is only occuring with 1 of the three batteries that I purchased.

Any recommendations?

I've seen this error before but it's always been under warranty so returning it to DJI was the easy fix. You can try and downgrading the firmware as far as you can, then upgrading it to the latest, if that doesn't work and your desperate you could probably replace the intelligent board/connectors in the battery, but I've not done this for this issue before so i can't give any guarantees it would work.

Ben Mason Posted at 2019-10-7 00:03
I've seen this error before but it's always been under warranty so returning it to DJI was the easy fix. You can try and downgrading the firmware as far as you can, then upgrading it to the latest, if that doesn't work and your desperate you could probably replace the intelligent board/connectors in the battery, but I've not done this for this issue before so i can't give any guarantees it would work.

Thank you for your reply. (This reply is 1-1/2 years after yours).

I found a temporary fix: Connecting the drone to Assistant and doing a Factory Reset. This has worked twice, so far. After the first factory reset, the battery error had not reoccurred for at least 6 months, but randomly returned about 6 months later, without any apparent cause. Again, this is the only battery (of 3) that had been generating this error.