The EEE indication on the display is telling you that there is a problem with the electrical connection to the iron. Typically the EEE is an indication of an open sensor circuit which can be caused by either a failed heating element or an open in the handpiece.  You can check for both by using a multi-meter to be sure that the heater and sensor circuits are not open.

If you have been able to verify that the heater and sensor cirucits are not open, then the problem is with either the connector or PCB inside the unit.  It is recommended that you contact 1-800-88-HAKKO (42556) and request an RMA to return the unit for service.