my 3 1/2 yr old son has NO interest in potty training?

It sounds like he is trying to control what is going on. Children have little control over things in their lives, so the potty can often be something they try to control.

I would suggest stopping the power struggle. If you know he can hold it, toss the diapers and get underpants. If he pees his pants, tell him to change himself. If he struggles a bit to get his clothes on himself, that's ok. Make him do it himself. Don't stand in the bedroom as he changes or do it for him, just go about with what you are doing. When he changes out of the clothes make him put them in the laundry basket. He should also be cleaning up any mess on the floor.

As far as incentives, you need to find something he really wants. Candy is not working, so find something else. It must be something he does not get any other time. He must only be able to obtain it by using the potty. It has to be something he will work for. For example, if he really enjoys playing computer games, that would be something he would earn. 10 min for every time he goes on the potty. He would not be allowed to play any other time, this includes at preschool, or grandma's house, etc.

Keep a diaper on him. You can't push these things. He will be trained when he is ready, like your other son.

My son decided to be trained when he could only attend preschool, if trained. We did use stickers attached to the toilet tank, and had a little bag of very small toys he could pick from if he had a certain number of successes.

But, all in all, they train when they are ready. Before that, it is a struggle for attention with the whole thing. Most say, kids don't usually go to kindergarten not trained, so don't worry too much.

You could also go to the store with him and let him pick some "big boy" underwear - the kind with cartoon characters and such on them. Let him know that when he is dry/clean for a certain number of days, he can switch to those.

Put them in the drawer, and make no more mention of it. Keep plain diapers or pull-ups on him, in the meantime, if you can'

You just have to stick with it. At 3.5 it's no longer up to him to be ready, it's now up to you to make it happen. If incentives aren't working in the long run, then try punishments for going in his diaper during the day, like no dessert or take away a favorite toy.