You should start with checking the powersupply.
Test over the caps C4,C6 and C8.
C4 = 9,1V
C6 = 4,9V
C8 = 10,5V
When you start the refridgerator, do you hear a click sound after 1 minute from the powerboard?
Does the buzzer sound the alarm?
NOTICE that the relay dosen't activates before 1min after you pushed on/off and you have "-" in the display.
Also notice that all the voltage on the powerboard is dangerous because of the non isolated powersupply.
CPU'n:
http://www.datasheetcatalog.org/datashe ... 6l4p3y.pdf