2 issues that may or may not be relates.

My battery, and a new battery both power on my AC.  Remote connects etc...but my batteries are showing 0%.  Ive cleaned contacts so im at a loss.  Do i need to update firmware on my batteries?  If so...how?

Next issue is the IMU callibration error.
Will go all the way to 95% and fault out.

Any help is appreciated.
Phantom 3 standard

I got imu to calibrate but battery signal error help needed

Have you cleaned the contacts of the drone which is inside the battery compartment? Did anything happen before, like firmware upgrading?

The 2 main connectors for the batteries is the only place the power is applied to the drone.  The other 2 contacts that connect to the 4 pins in the battery compartment are for communication to the battery from the microcontroller and from the microcontroller to the battery.  This is how the 2 communicate.   If there is anything in the way like corrosion or some sort of paint or other foreign object, it wont allow them to communicate.