LG GR359SQ any help please ?? and thanks in advance

OK
Had this unit 6 years worked fine intill 1 week ago ,Wife thought boy left freezer door open as food was getting soft ,next day we found out just not getting cold top and bottom ,ordered a new fridgefreezer got fine all ok ,So before i take to dump i think maybe have a look see if i can get going and use as a second 1 in shed ,On the pcb at top behind leds i got out has a test button on it i pressed it a BANG all booted up fine works perfect ALL LIGHTS LIGHT UP AND STAY ON but comes out of test mode in few hours ,So i orderd a a therm plc and fitted to comp but still did not boot up after 15min but still works in test maybe 2 hours maybe 10 hours then just comes out of test mode and starts cooling down ,im going to take pcb in to work to check over from skilled person ,just wondering if any 1 can help out if possble please

Once again many thanks for ur replys
GAZ