Thank you for bringing this issue to our attention via the community.
We are sorry to hear that you are having problems with your Anker jump starter. As suggested by @elmo41683 and @bill_rae, could you please recharge the Anker jump starter to full and then try to jump the car with the following steps?
Make sure the red clamp be connected to"+" end and black clamp to "-"end of the car battery?
Please turn on your car headlights (to low down your car battery’s voltage) and try to jump start your car again after 30 seconds. The LED light on the jumper cable wouldn’t turn green if your car battery’s voltage is higher than our jump starter’s voltage and therefore you’re unable to jump start your car.
Move the ‘-’ cable from the car battery, then connect the black clamp to the ‘-’ cable directly, and the red clamp still connected to"+" end. Turn on your car headlights, and press the reset button for seconds. Try to start your car again!
Know that the Anker Compact Car Jump Starter can only jump 3L gas(Max.) or 2.5L diesel(Max.) vehicle engine. Please make sure your car’s engine is within the specs.
Hope this is helpful. Thanks for your support.