Thanks for all the help guys! I forgot to say this earlier, but apparently it got fixed again. My dad cleaned up the xbox a little bit without opening it, and now it works fine again. So I guess it was the dust. And the weather cooled down a little bit in Holland too, that might've also helped. Feel free to leave this thread open/unlocked though, maybe it can serve as a helpful source for people with similar problems.
Kinda a separate topic but it's probably better to have a general xbox issues thread than ten of them. My xbox occasionally decides to stop recognizing it's built in wireless card and tells me I need to plug in a wireless adapter to connect to a network until I restart it. It also occasionally starts making a sound similar to cutting steel with a dremel which will go away on it's own after a while. These are not related at all and both started fairly recently. It's still under warranty so I could send it in but I'm guessing they'll just say there's no problem and send it back. If that's common I could cause a CD to shatter inside it hopefully smashing enough stuff inside that they have to replace it. What do?
Oh, god no! Don't take it apart, and certainly don't hoover it :| If you need to clear dust off of any electrical substance with exposed circuitry, you need to use a compressed can of air that blows dust off. If you use a device that sucks, you're more inclined to make contact between the plastic nozzle and the component... which when a constant stream of air friction is being blasted off of a plastic tube's interior, generates a hell of a lot of static which will make your xbox go to sleep for good! If you use something that blows, you generally hold the can further away and there's little chance of you making contact via the static touch of death.
Don't just use any old air either, you need that special "clean" air that you can get, otherwise you'll just be blowing more dust particles through it. You can buy "clean" air in most good hardware stores.
This is good advice in terms of compressed air vs. a hoover, but why shouldn't he open it? This is bad advice. The towel trick is A) a last resort, and B) to fix red ring, not overheating. The towel trick basically forces the xbox to overheat, and the reason it's used to try and fix red ring is because it's an easy but incredibly clumsy and dangerous way of trying to re-flow the components which are faulty (I believe it's the graphics in the case of red ring). Be very wary of the towel trick. I've done it, but it should be used on boxes that are red ringed and you don't care about totally killing if it means a chance at fixing it, and you don't want to spend any money on it. Also, as I said, it's not of any use when trying to fix overheating. You're essentially saying he should fix overheating by forcefully overheating, I'm afraid this makes no sense.
wow. My xbox red ringed and the first solution I found was the towel trick. Thank god it didn't **** up.