Because it is a light shoe is not a USB interface, a battery on the sole accumulates electroluminescence with time sometimes leads to non-luminescence, a bright one is not bright, or a bright one is dark is normal. If there are light problems such as the left and right light and dark are different, the left and right light depth one will be bright one will not be bright, color imbalance and other problems we are not as a quality problem to deal with the mind carefully shot!!