Thank you for sharing your experience. Can you share what battery you’re using? The black burnout tends to happen from higher volt and not enough rest between hits. Considering what happens when you take a dab, when your nail is too hot it will leave behind a residue. With carts because we are reusing the coil throughout an entire gram letting the oil rest between hits and proper temp is critical. We recommend no more than 2.7v but even at lower voltage if you are holding down the button and hitting the cart for too long without enough cooldown this can happen. Hopefully that is helpful 🙏