BatteryLevel not working!!

It's not going to be that useful asking about bugs in the Unity XR implementation here.

If you're targeting Oculus Quest why not use the Oculus Integration and the classes/methods provided by Oculus?

/// <summary>
/// Gets the current battery level.
/// </summary>
/// <returns><c>battery level in the range [0.0,1.0]</c>
/// <param name="batteryLevel">Battery level.</param>

OVRManager.batteryLevel

Then this thread title probably didn't need the double exclamation points!! That kinda communicates an urgent blocking issue, not something that can be solved with googling.