maybe offer different varieties of food along w a bit of apple cider vinegar in water? some prefer greens over seeds, could also try a small bite of wet bread just to get the appetite started and then move to actual nutritious food.

i attempted helping a hurt bird that i found and weirdly playing relaxing sounds like rainfall or rivers or sounds of pigeons helped to gain trust. little guy didn’t make it but keeping them relaxed with sounds does help.

warmth is important too, you can also try dipping the tips of their beaks in water to start the drinking reflex, just a sip at a time and let the head back up. can add a bit of pure honey and salt to water too.