He will learn sooner or later. I was scared about my little brother. I was like ohh no, he will never learn how to write but now he knows how to write full sentences.

I have a four year old also and how I started him out on tracing his name, I made the dots myself for about a year and then I found out about education.com and they have traceable printouts and you can edit the worksheet by typing in the child's name and then have it printed. But like I said before if all others fail make the dots yourself. It is time consuming but at least you know that your child is getting that help.

When I was working with special needs children I learned sensory development and found the techniques used for learning to write transferred to preschool students too.
First we give a tactile experience of tracing the letter either in sand or rice. Then we moved on to tracing the letter. Then we had child write letter independently without lines. Lines came in at age 5.
I also love the new Mead learning to write cards which give you sky, grass, earth perspective on writhing letters in lines. ;)

Please do not read too much into his behavior with his homework.  Some boys (and girls) fight writing.  They eventually grow into it around the end of kindergarten/beginning of 1st Grade.  It is no indication of his level of intelligence, his willingness to learn, or his focus skills.  The same children who disdain writing also seem to have no interest in coloring, which is a primary 'skill' in kindergarten.  My son could have cared less about writing or coloring until recently (he's a 1st Grader, with fine penmanship, surprisingly enough).  I decided that until he was actually in real school (i.e. kindergarten), I wasn't going to make a big issue about it.  We focused on things that he found fun, reinforcing how much we enjoyed learning and how school is a place where learning is fun.  I found that even though he didn't like writing or coloring, he was really good at basic addition and subtraction at an early age.  Additionally, I decided that formulating cohesive thoughts was a more important skill at that age, so I had him dictate his own stories to me, which he would watch me write.  I would discuss the motions of the pencil as I wrote them.  Then I would let him illustrate the story by using a computer drawing program.  You are energetic and enjoy your child's company - so be creative and give him a more important skill than just writing or answering questions (that are probably too remedial for him - maybe he's bored?) - help him identify the fun of learning through honing his personal intellectual strengths!  Then you can clandestinely weave in the 'not so fun' stuff, like writing and coloring.