First, factory reset your PS4. Navigate to Settings, then Initialization, then Restore Default Settings. Follow the on-screen instructions and remember to back up your data if necessary to avoid data loss. Then, clean your PS4. Start by turning it off, unplugging it, and gently dusting the vents and exterior with a soft cloth or compressed air. Lastly, take some photos and list your console with the e-commerce site or resale shop of your choice.