C-0204 The Lift-up Sensor is not blocked even after the
lapse of a given period of time after the lifting
motion has been started.
Basically your paper tray 2 did not lift right. Open the tray and make sure the paper is loaded correctly. The paper should be touched on all four sides by the tray or by adjustable guides. Open and close the front door with the tray out. Once the machine is ready to copy close the drawer you should hear a slight buzzing sound as the tray rises. If you don't or you hear a banging or grinding sound the tray lift motor may be damaged and you will need to call a service technician.
If the code keeps coming back pull out tray 2, open and close the front door to reset and leave the tray 2 partially pulled out until a technician can repair.