Although it is a rare occurrence, the firmware of the HAKKO FP-102 Soldering Station can be corrupted by removing and then re-attaching the handpiece while the power is on. The system will display an error condition where all four of the indicator lights will be illuminated and the station will not heat.
In order to reboot the firmware, you will need to carefully remove the cover of the station, short the small jumper on the PCB, briefly turn the power on, and then power off the unit and remove the jumper.