Checks / troubleshooting:
Check connection between HEATER
CONTROL board and MAIN board .
Check if green LED is on HEATER
CONTROL board is on.
Check if red LED is on HEATER
CONTROL board is blinking.

Recommended actions:
Reconnect HEATER CONTROL board
and MAIN board .
Or replace cable connecting HEATER
CONTROL board and MAIN board .
If green LED is still off after turning on
power, replace HEATER CONTROL
board .
If red LED is blinking and there is no
problem on connection between HEATER
CONTROL board and MAIN board ,
reinstall firmware.