No there is no VBatt pin. All the Vdd pins connect to the 3V3 step down converter. A 3V battery is connected via a diode to the Vdd pins. As long as there is power, the MCU gets power from the power supply. Once the power supply dies, the MCU gets power from the battery.
Do you know how I would sense that there is power to the MCU again so I can re-initialize the display?