Sparrow with beak stuck open

  Hello RSPB community. Today this sparrow appeared on my balcony - he has his beak wide open and is trying to feed but can’t, he just wiggles his tongue around. He’s been drinking, and can fly. Is there anything I can do for him? I crushed up some nuts and seeds in a blender in the hope he could scoop them up somehow. It’s so distressing to see him trying to eat :-( I can’t tell if it’s an injury or a disease of some kind. Any advice would be welcome. Thank you!