Because the Light-on Shoes Are Not USB Interface, It Is a Battery of the Sole That Stores Electricity and Emits Light. Sometimes the Loss of Electrons over Time Will Lead to Non-Luminous, it Is Normal That One Light Is Not Bright, Or One Light Is Bright and One Dark. If There Are Light Problems, Such as Different Light and Shade on the Left and Right, One Light on the Left and Right Will Be Bright and the Other Will Not Be Bright, and the Color Is Uneven. We Do Not Treat Quality Problems Carefully!