How do I verify Chinese used car رقم الهيكل before paying deposit?

Require five things: (1) chassis plate photo — full 17-char رقم الهيكل visible in single frame, (2) engine bay رقم الهيكل stamp photo — must match chassis, (3) ownership certificate (机动车登记证书) scan showing matching رقم الهيكل, (4) vehicle registration certificate (行驶证) scan, (5) walk-around video minimum 30s continuous with رقم الهيكل plate visible in single sweep. Position 9 is ISO check digit — verify formula. Chinese رقم الهيكلs start with L.