String Trimmers

I recently purchased a PPB40T 40v battery trimmer. After using the trimmer for only a short while it will just stop and one of the LEDs above the "speed" button will flash. This LED has a triangle with an exclamation mark. The battery has plenty of charge and trimmer does not feel warm. If I turn it off and then on again it will run for another 10-15 seconds then stop again, same condition. The manual has no mention of this condition.