The safety restraint system in a Mercedes can malfunction for several reasons: low battery voltage prevents the system from functioning properly; failed sensors inside seats prevent the system from detecting collisions; water leaks can damage safety components; and failed airbag sensors prevent the ECU from knowing when to deploy airbags during a collision. Neglecting issues with the safety restraint system can lead to serious accidents if airbags fail to deploy in a crash. Regular maintenance and diagnosis of components is recommended to detect any issues early.