My white XL batty is not charging !!! i let it charged for 4 hours , put on the cart and the led blink for 1 sec and turn off. I stick it in the usb charger and the led blink few times and turn off ( the led suppose to stay on ??? my other XL black batty's led stay on ) . The usb charger gets really HOT and smell like burnt ! , i received my order yesterday and now this happened ?