Protein would be a hard cooked egg, tuna in water, chicken well cooked, yogurt, cottage cheese in small amts. For calories you could feed 2 or 3 nutriberries per day (my vet suggested this).
Be aware there may be a blood feather protected in the wings. They usually only have one or two at a time. You can look up on the web how to deal with a blood feather if it should become dislodged. Better to know ahead of time.