Help with duckling

[Tabi]

One of my dad's baby ducks were born about a week ago and ever since he hatched he has not been able to open his eyes, sleeps a lot, stumbles when he walks (I'm thinking this is because he cannot see), and doesn't seem to be growing. I do see him drink a little bit but I haven't seen him eat. Another ducking was born the same day as him with maybe only an hour difference and he is three time the size and very lively. My dad won't take it to the vet so I am searching for answers here.