What else is shown on the display, and are any of the numbers flashing?
This is defiantly a hardware fault, most likely to be one of the thermostats, while the fridge was running the thermostat was probably constantly calling for coolant, and that generated the error and hence why the compressor was running continuously. By switching it off, when it was switched back on it did a self calibration and determined the thermostat was no longer calling for coolant thus the fridge freezer thinks its at the right temp and not running the compressor.
Due to the way the thermostats are mounted in the modern fridges it is worth getting an engineer out, as there is a nack to stripping them down without damaging the insulation and plastic fascia.
If you would like me to recommend a suitable engineer, please provide me your post code.
The wiring diagrams are in the service manuals, Beko like most manufacturers release them on licence to approved service centres.
You can find a few which make them on the internet, but there isnt any official channel to get them, I generally only use them when I discover lose wires and need to know where to place them on the PCB.
Another source is the Espares technical department, they are designed for the consumer market and often go out of their way to help for free if you tell them you about to order a new PCB or sensor.
The local engineer we have used for other customers in your area is Mike, he has repaired a number of america fridge freezers and have always had excellent feedback from his work, his number is *****
I just wanted to follow up and check if you required any further assistance, and request you rate the service received so I may resolve this case.
Thank you for letting me know about the concerned repair firm, I will follow this up. From the conversations I have had to date from other customers (5 this year) who have used Mike have only had good things to say, not sure if its a case of not setting expectations or actually the quality of the workmanship, but ill certainly look into it.