Arthur sighed. If the previous admin had been "creative," he’d have to perform a factory reset via maintenance mode. But before opening his toolkit, he checked one last thing. He walked to the back of the printer and squinted at a small white sticker. He noted the serial number and typed it into the password field.
Alternative: For newer firmware versions or different regional settings, try admin (lowercase) for both, or the device's . How to Find Your Device Serial Number kyocera m3550idn default password