I did a search for it and found no results so here is some info. Sorry if it's been reviewed to death, but it's new to me.
P3P using 1.5 the other day after a 3 week health issue. Arrived on a job 2 hours away, got everything setup and wham, a very loud beeping! Full camera control with still and video working. No motor control at all. Go app said latest firmware and acted normal. Going through all the settings I eventually noticed battery power at 0. All LEDs on the batteries are lit and the same results with 3 fully charged batteries! Installed a new 32 gig high end card, same result. Eventually hit aircraft status and see in red, Battery Connection Broken. I gave up, went home and started searching. Hey firmware 1.6 is out. Downloaded it and started the install and sure enough that dam beeping started but this time it stopped after a few minutes. The loud beeping not the normal update beep or as dji calls it " D-DD".
I ran all three batteries through the update just for good measure and I'm vertical again!

But DJI????   Is this the new mandatory update process if the go app fails to warn of update required? Just a very loud beeping and a Battery Connection Broken warning.

There is no mandatory update required so I don't know why your batteries said zero.
Had you not charged them after the 3 week period. They should have went down to storage level.
Glad its working now though.

DJI-Ken Posted at 2016-1-28 17:27
There is no mandatory update required so I don't know why your batteries said zero.
Had you not char ...

Thanks Ken and neither do I, yes all of them were at 100 percent and after the 1.6 update they were still in the upper 90's without hitting the charger.  Obvious code writing issues somewhere if the app says 0 and the batteries display 100 and the camera/alarm works but motors are dead.
Maybe just another freaky gremlin but firmware code is mass produced.