Bosch Fridge Freezer Control Panel Problem

[Bork]

Hello. Please can someone help/advise. I have a KGU3102/GB Fridge Freezer which has never given any problem. A short while ago the Control Panel stopped working (apparently). There is power to the panel housing unit, the on/off and door switches work, but the LED Temperature readout is not illuminated, and the compressor and other button controls on the "PC Board" unit do not work. A local engineer called and checked, advising that a replacement PC Board unit was required.

We agreed I could get a new one and fit it on receipt, as it just plugs in with two standard white terminal blocks. I have obtained a new PC Board, and have plugged in the two terminal blocks into the PC Board/Control Panel unit - but it does not work!

Please can someone advise what the likely fault is and how to repair it?

Thanks in advance.

Bork

[SaFill]

Sub Zero 550. Seperate fridge and freezer controls/thermostat/compressor. Fridge working fine. Freezer will run fine, go without issue for 1-2 day period. Temp getting very low
Thanks.