Fiat Duccato breakdown

2022 Fiat Duccatto won't run following the driver putting adblue in the diesel tank. Had it fully flushed through and filters replaced but won't start. He claims he started it but shut if off as soon as he realised what he had done. Unsure if there is air in the fuel system or if engine components are damaged. This needs investigating on site in Hinckley due to the size. The vehicle is converted by maxi mover so is 3.3m high x 8m long.