Can you follow the steps below to test the light and battery?
1. Remove the tail cap. Rotate the Octagon ring clockwise to tighten it and ensure it is fully settled on the body tube.
2 Install the battery and the tail cap. Fully tighten the tail cap.
3. Check the light head to make sure it is fully tightened to the tube.
4. Connect the Micro USB plug of the charging cable to the light
5. Connect the USB plug of the charging cable to a powered USB adapter or a computer USB port if you are not sure whether the adapter is good or not.
6. Observe the blue indicator beneath the front side button.
(1) If the blue indicator flashes rapidly, press the power button on the tail cap as if you are trying to turn on the light. (there will be no beam output after you click)
(2) If the blue indicator blinks slowly (once per second), the light is charging the battery.
Full charging takes about 6 hours. When it is completed, the light will terminate the charging process automatically.
In short, the power switch needs to be turned on to activate the charging