To charge your CO. Worker, turn the brush upside down and look for the cute little arrow on the base.
Where the arrow points is where you should use your nail or common-sense-tool to pop it open, revealing the charging port.
Then just plug in the charging cable. The little “smile” under the CO. lights up and pulses while it’s charging.
FYI: When your brush is fully charged the “smile” stays solid white. When the “smile” flashes red that means your CO. Worker is hungry for power. Charge it up!