I am getting a B200 error on my MX850. I realize that this typically means the print head is done, but in this case I am not so sure because when I lift the lid, nothing happens at all. I would expect if it is a faulty print head, that the carriage would still travel to the center (allowing you to remove the cartridges and print head), but nothing moves or does anything at all. I have tried turning it off, unplugging it and letting it sit a few minutes before trying to restart it, with the same results. Is it likely a faulty main circuit board?