Good day Joe! There are a lot of reasons why your printer could stop working and error code COOO represents it. I had the same problem as you, so I called a guy from mrdepot and he explained me everything that can happen to the printer and how to fix it. To be honest, it is a not a big problem and you can do everything in 10 sec. So, the first problem can be the incorrect position of the ink tank, the most faced one. Second, is that a piece of paper can be jammed or there is something in the printer. And the third, is just the need to reset the printer. Hope I was useful, good luck!