I try talking to him but he won't listen
For the past few months my son, age 5, has been fighting with us over everything. He won't listen to a thing we say.
He's probably feeling a leash and is pulling on it.
See if this might match what's going on: You see your role as orchestrator. It's your job to make sure things run smoothly and everyone gets what they need in a safe manner.
If that's so, then Jaiden may feel he's being orchestrated.
If you mentally switch the role you're playing in a situation, how you react to the situation will change and your view of what an action means will change. If Jaiden runs off it won't be defiance but enthusiasm.
If we see an action as defiance it's natural to want to stop it. If we see the same action as energetic enthusiasm that can't be contained we can revel in that feeling and more patiently and understandingly help them rein it in temporarily until we can help them. If you're reacting differently to the same behaviors, Jaiden's need to pull on the leash will decrease since the leash won't be there any more.
Today he wanted to do something on the computer, and while I was setting it up I asked him not to press any of the keys (we have been having computer problems lately and it's been freezing up) I explained all this to him, he looked at me and started pressing a bunch of the keys, he crashed the computer.
Part of it may be because he's 5. He's testing out his independence. There are various stages kids go through where their world view shifts and 5 may be one of those stages. For instance -- if I'm remembering correctly -- when they're infants they view everything around them as extensions of themselves. Then one day they realize there's too much that doesn't make sense for that theory to be true and they realize everything they knew was wrong! ;-) So they need to test out their world to come to a new understanding. It could be he's going through that testing out phase. He's realizing he has power over the world and other people. He's realizing he can try things out and not just take people's word for it any more.
If you see the situation that way, that's a good situation! In fact we get frustrated with adults who mindlessly take in what they're told without thinking about it or trying it out for themselves! But if children do the same, we get frustrated because that's not convenient for adults.
But if our goal was convenience, we shouldn't have had kids ;-)
Another part is he, like adults, prefers information to being told what to do. If you approach the situation with information "The computer's acting futzy and if you press random keys it's very likely it will crash," and then expect he'll test or not test, then there is no power struggle.
It's not a dangerous situation so it's not an experiment he needs protected from. Save your don'ts for danger like running in the parking lot. If you see your role in the situation as you taking time out of your busy day to do something for him, then it's going to be irritating if he makes the task more difficult for you. But if you see your job as his helper in exploring the world, then testing keys to see if the computer really will crash is part of that exploring. Shifting viewpoints can help you get to a mental place where what he does isn't irritating and you won't feel you need to stop him from doing it.
He got mad at me when I told him that he couldn't play on the computer until we got it working again. He went in his room and began beating on things with Jason's bike pump. Broke the bike pump. When Jason tried talking to Jaiden about it Jaiden stuck out his tongue told Jason "your not the boss of me" and slammed the door in Jason's face.
Obviously the situation had deteriorated by that point. If you look at that objectively and not as a parent trying to control a child to behave in acceptable ways, you can see that he was supremely frustrated at his lack of power and control and being in a situation where others have power and control over him. And he was enraged.
If we saw that same scenario translated into a slave and master relationship, we'd totally sympathize with the slave. We'd understand his rage against a situation he had no control over. We'd understand that everyone craves freedom and no one wants to be told what to do and how to live. Everyone wants control and power over their own lives.
And we can give that to our kids. Not by letting go, but by walking along beside them and seeing ourselves as their facilitator in their exploration of the world. We can be their source of information, and their "spotter" to keep them from being hurt too badly in case they fall. It's also helpful to see our information as a piece of data in their decision, not the decision they should come to. Sometimes testing something out will be worth the consequences. Sometimes pressing the keys to see what happens or to see if mom's right is worth the crashed computer.