How do I check the remaining battery level on the WH-1000XM4?

Press the POWER button while the unit is turned on to hear a voice guidance announcement of the remaining battery level. The unit will announce levels such as 'Battery fully charged,' 'Battery about 90%,' down to 'Battery about 10%' in 10% increments. When the battery is low, the unit will announce 'Low battery, please recharge headset,' and will say 'Please recharge headset. Power off' before automatically shutting down. (Page 1)