HELP my budgie needs saving , ill do anything to save him

(URGENT )I have a 3-week old baby budgie whose mum has abandoned. his head is severely injured by another female who tried to kill him, he is very small and undergrown and tiny for his age and his legs are splayed and his feet haven’t grown in a correct way and has deformities in them and his wings also seem to be abnormal. Now I have to keep his nest warm and feed him and treat his feet and head, what should I do and how especially warming his nest and treating his head and feet?. if anyone knows anything I would be very grateful for an answer (we have no vets in our country) (limited resources in my country)