Your flame sensor is bad. The contacts inside it are fried together. You be the flame sensor. Carefully remove a wire from the sensor while that ignitor is glowing. If you get ignition you know your flame sensor is either out of position or contacts inside are fried together OR the bi-metal inside the flame sensor is bad. That wire you disconnect can bite you. Have a way to easily kill power to the machine while you are working on it. Or better yet have a friend standing by to unplug the unit for you.