Release the pedal after stepping on the brakes, the pedal does not rise, no resistance, this phenomenon is The brakes do not return. Need to judge whether the brake fluid is missing; brake cylinder, piping and joints. Is there any oil leakage? Is the main pump and sub-pump parts damaged? If the user cannot check it himself, If you check or solve such problems, you should promptly send them to a professional service center for inspection and repair.