Put a piece of electrical tape over the window of the empty cartridge. If you don't have electrical tape, do what I did and cut out a small piece of the sticky part of a post-it note and pen some black ink on it. Tape it over the window and insert into your printer again.
How does it work? The sensor on the printer thinks that the cartridge is full due to the darkness of the pen and you can print black and white now.
It's a miracle!