The wound does not look too bad. You can put some antibiotic cream on as well. Looked like he got attacked by an older pigeon, there might be something else wrong with him. Can you take a flashlight and check inside the beak and back of the throat for any unusual yellow cheesy or whitish growths? The inside must have a nice pinkish colour.
An easier way of feeding: Mix the handraising powder with a little bit of water to form a soft clay. Then make small peasized balls and handfeed to him by placing one at a time deep inside the beak over the tongue (if the inside is clear of any growths). Easier if you have him on your lap. Feed him about 90 balls per day, divided into 3 meals of 30 each. Let him drink water after feeding. Make sure the crop empties inbetween feedings.
An easier way of feeding: Mix the handraising powder with a little bit of water to form a soft clay. Then make small peasized balls and handfeed to him by placing one at a time deep inside the beak over the tongue (if the inside is clear of any growths). Easier if you have him on your lap. Feed him about 90 balls per day, divided into 3 meals of 30 each. Let him drink water after feeding. Make sure the crop empties inbetween feedings.