Yes, I think he did get a new bird, since it's listed in his profile and he's already named the bird...
And he admitted that he had no idea why his Green Cheek died at only 8 months old, and he refused to get a necropsy done. So unfortunately, if it was an illness/disease, or it was an environmental factor such as Teflon fumes, etc., then it obviously can happen again...The OP made the statement that he "always kept his Green Cheek away from fumes and such", but I don't think that he understands that even keeping his bird in a separate room behind a closed door will not protect the bird from someone cooking with non-stick pots and pans in the kitchen. I had asked him whether or not his parents used non-stick pots and pans, bakeware, etc. that contained Teflon (I mentioned that they usually have the black coating on the inside of them if they contain Teflon), but he never answered the question, he only stated that he would "keep his bird away from the fumes". Based on that answer, I assumed that it may very well have been fumes that killed his Green Cheek, as again I don't think he understands that Teflon cookware/bakeware cannot be used at all inside of the house. And his Green Cheek was only 8 months old and he died very suddenly out of nowhere.
The OP is only a kid, a teenager I believe, and he does seem very responsible about his bird, though I have to admit that I'm kind of shocked that he ignored all questions/advice about what may have killed his first bird so young and so suddenly, and just went out and bought another bird without first checking everything out inside of his house, so that this won't happen again.
So to the OP, please, since it's too late and you've already gotten a new bird, then all you can do is make sure that you first completely disinfect EVERYTHING that your Green Cheek ever touched, everything, every toy, dish, perch, the cages, etc., everything, in extremely hot water and either Bleach or F10 disinfectant, as regular cleaners will not kill everything. And if you've already done that then that's good, but the next step is MAKING CERTAIN that your mom/dad do not have ANY pots, pans, bake pans, etc., any type of cookware that is heated up on the stove or in the oven, that contains ANY non-stick Teflon coating (usually any with the black coating), and you must make sure that your parents throw them out and buy either ceramic non-stick pots and pans, bakeware, etc., or aluminum, cast iron, etc. Unfortunately most pots and pans do contain Teflon, at least the most commonly purchased ones, and just keeping your bird in a separate room from kitchen, even behind a closed door, will not keep him safe from the fumes of Teflon. The way you described your bird dying did very much sound like he was killed by some type of toxic fumes/smoke/vapor etc., and closed doors and separate rooms will not protect your bird. Also, it's not just cookware and bakeware that contain Teflon, it's also lots of normal, household appliances, such as space heaters, air conditioning units, hair blow-dryers, curling irons, etc. Also, any cleaners that are not all-natural and made from plant enzymes or just simply vinegar, any cleaners that are scented in any way, are toxic. Candles, any type of plug-in room scents, incense, essential oils, oil burners, any type of powders that are sprinkled on the carpeting before you vacuum, even the Arm & Hammer Baking Soda carpet powders that are "made for pets" are extremely toxic to birds; any type of smoke, even if it's done in a room behind a closed door that your bird never goes it...Birds are so sensitive to any and all of these types of things due to their very complicated and sensitive respiratory systems and air-sacs, that it takes literally only a whiff and that's it...It's usually either the non-stick Teflon coatings or household cleaners that are the culprits; the non-stick Teflon fumes work very quickly and there's little you can do, and household cleaners, even if not used in the room where your bird is kept will be toxic to him if he goes anywhere near where they've been used, as they cling and stick to the surfaces that they've been used on for quite a long time.
We are only worried that you're going to have this new bird pass-away as well in the same way; I wish you would have had a necropsy done, you still could have buried your Conure after the necropsy was done, and that way you would have been able to remedy what the cause was before bringing another young bird into your home. It would just be terribly traumatic for you if this bird too passes away suddenly..