Use the following steps to perform a Factory Reset:

1. Turn the printer off.
2. Hold in the circular button on the front panel of the printer.
3. Turn the printer back on.
4. When the DRUM light is lit by itself let go of the button.
5. Hold in the circular  button on the front panel again.
6. Once the Alarm light comes on, let go of the button.

This has performed a factory reset on the printer.