I think his feathers just haven't grown in yet. It does look a bit young to be fledging tho. Are the parents near? Can you see his next and put him back?

That baby bird is still fledging since it is still young. Maybe that's the reason it has bald spot. Good thing the baby bird's mum is always their for him/her to give him/her food. Do you still have the baby bird or it flew away together with its mum?

It's much too young to be leaving the nest and the bald spots are either undeveloped feathers, or nest mates may have plucked a few feathers.
I suggest soaking some dry dog food in water and setting it out for the parent bird....this will make feeding the chick easier and also provide a nutritional diet for the chick. If the Maya will eat it, you can also offer canned dog food. You've done a great job and the parent is definitely dedicated!
I would try raising the chick higher in the basket by placing mats, cardboard or papers under it's bedding. Raise him enough so it's not so difficult for the hen to feed, yet keep the sides tall enough so he can't easily fall out.
If you can keep cats and dogs away it has a good chance of survival.

Sorry for the year late reply. It was a happy memory.

I assume that means it died?

And a happy ending~ haha. It was healthy and attempting to fly last time I saw it.

Ok..........that is good news! :)
When I read 'memory', I thought the worst. BTW, great idea to tie the basket up high.