1. Check if there is any dirt inside the earbuds' copper pillars and charging casepogo pin.
2. Lightly shake the earbuds' case to ensure the earbud and pogo pin are in close contact, and try charging again.
3. Place the earbuds in the charging case and connect the charger for 10 mins, and try charging again.
4. Open the case and long-press the pair button for 10 seconds until the notification light is on; then try charging again.