1. Check whether power supply cables are connected and plugged into the printer correctly.

2. Check if the imaging unit is completely installed inside the printer.

3. Turn all switches ON and OFF several times, including the printer and imaging unit.

4. Turn off all power to the printer and unplug the printer from the wall.

5. Leave the printer disconnected from power for at least 60 seconds.

6. Reconnect the power and turn the printer and imaging unit switches back ON.

7. Check if the printer is still not recognizing the new imaging unit.