Turn off the machine. Gently remove the printer head (instructions below) and check to make sure that the ribbon cable is completely inserted. If it is, remove the ribbon and check the pins to make sure none are bent or broken. (If so, provide a picture here.)
Reassemble everything, using the instructions at that link, and print the Gift of Good Measure on the spare sheet of draftboard that the team provided for troubleshooting purposes.
Link to instructions for printing the Gift of Good Measure:
Let support know the results of that print. Good luck! 