Dixell Wing Controller on an Ifrico ZX2 Pentland Bottle Cooler

I have an Infrico ZX2 Pentland 2 door Bottle cooler. It has worked fine for about 6 years. It then developed a fault, whereby, the outside of the double glass doors were covered in condensation and the inside temperature was at ambient.. On the Dixell Wing XW20L controller the alarm LED is permanently lit. The latest literature does not help me to sort out what is wrong and how to reset the controller as the literature is dated 2015. I hold my hands up to admitting, I have tried to grope my way to sorting it out how the controller is operated, but fear I have messed up the basic settings and can’t find a Factory Reset? Also I can’t find what the ideal setting should be?
I have placed a thermometer inside the cooler. It confirms it is cooling down to around +4 C. I have checked the areas all around the heat exchanger are clean and clear. The two fans inside are running freely. I can feel the draught of air blowing up through the heat exchanger, I can feel and hear the compressor running. So it seems it is working as it should in those areas. I have set the ‘Set Point’ to +2 C. I don’t know how to set the upper and lower temperature limits I want to control the temperatures between – say + 4 & 7 C. I can’t find where the thermostats are located or if it’s done on gas pressure how to set that? Where/how does it defrost? From my reading I think it works by stopping the compressor. How/where do the durations between being on/off get set? I note on some documentation it talks about resetting the Max and Min temperatures recorded? On the 2015 Dixell Emerson XW20L literature its instructions use some sort of mathematical symbols when describing how to set/change some of the parameters in the controller. These are not explained.
Please would someone be kind enough to help me ascertain what had caused the alarm, how to cancel the alarm LED and how to set the controller to operate between say + 4 and 7C.
I have some short video clips of the controller displays showing what outputs I got pressing some of the keys. but I don't know how to upload them?