okay
get a flat iron hair serum (got 2 be has some good ones, same with garnier and a few other brands - they treat your hair and help protect it some from excess damage) and smooth it into your hair. it will help a little bit...hair gets frizzy cause it's thirsty and/or damaged.
Try a lower heat setting if you can or dry your hair before hand (and use with the serum).
Make sure you condition your hair regularly and give it breaks from the extreme heat.
I use curd soap (soap, that makes your hands really dry). It might work with normal soap too. Just rub the soap between your hands with a little water, till you get this thick soap foam, then apply it to your hair. Now get a comb and blow dry it, just like you would do when spiking it.
It works for me, makes my hair really straight and sticky, easier to spike it afterwards too. Might be worth a try.
That could work, if is his hair isn't fried, and it had some form of tighter curl.
I think if it's fried (ie, dried out, too processed), it won't relax, because I don't see his hair being curly/kinky enough (could be wrong...) BUT along the lines of relaxing, you could use a deep conditioner instead, since it's frizzy and stuff. A henna placenta, v05, and some garnier (for extremely damaged hair, its like a mask) I've used and my hair has always been nice.
but if you've got the split ends too, those will need a trim, or you will see them.
Lets see, how short is it? I've found that if you put a hat over it when its wet, and let it dry it ends up pretty straight. I use like, a winter hat thing. And because it isn't using any heat, it doesn't kill your hair. Just.... wash the hat every once in awhile.