If you receive your new battery-powered device (e.g. headphones or portable) and it does not start immediately, it is probably not a defect, but a deeply discharged battery. A deep discharge does not normally represent a defect. Therefore, we recommend that you charge the device once for at least 24 hours using the supplied charging cable/power supply before making a complaint, which may not be necessary, in order to safely rule out a defect, even if the charging LED does not turn on immediately.
Tip: If you have a USB charger in your household, change it as a test if it was not included in the delivery. Many, especially older, USB power supplies only charge the battery with low power, which takes considerably longer or does not work at all.
More info on the topic:
ROCKSTER / ROCKSTER AIR: The battery does not charge and/or discharges very quickly. Is this a defect?