Beko TFF673APW stopped freezing

We returned from a week’s holiday to find that our 20 month old upright freezer had stopped freezing it’s contents. The freezer was still powered but red high temperature warning light was illuminated and the contents was either defrosted or partially defrosted. On closer inspection the fan and condenser were still working and fluid was circulating through the condenser. I could see no visual indication of damage to or failure of either the pipe work or the visible components. Any direction to what might be the potential cause and if it is viable to repair.