You sir are a national treasure.I really hope you used a microwave that is 3000W or higher. If not, what most likely happened is that the longer cook time caused the turbo encabulator magnetic seals to weaken, which led blue smoke escaping the vacuum sealed chambers. When this happens you generally have to desolder the GPU die (since it is located directly under it) and replace it with one from the same generation. I would recommend a Dyson hairdryer, it is cheaper than a hot air station but not as effective. However, it will get the job done, and make sure you get the three prong version, it is able to dissipate ESD. Unlike its two prong counterpart.
Reassembly is pretty straight forward. The only difficult part with be re-balling the GPU die. Now they make templates for some dies, which allows you to drop the lead based solder balls into the correct position. However, if you re unlucky and have to design your own, you can use a 3D printer or a 3D printing pen (a lot cheaper, but harder to deal with). After that, if you have a hot air station you can just heat it up till everything flows and seats and your done! The other way is to use a Coleman induction heater, small iron pipe (to transfer the heat to the die). But you cannot crank it to max without breaking something. So, use some painters tape to hold it down (doesn’t leave any residue behind), flip it upside down and balance it on the iron pipe, set it to mediums. Set the dyson blower to low, and just sweep back and forth on the reverse side of the socket.
That is only for the GPU die itself, since I never replaced a turbo encabulator before, it’s best to Google it and see how others have done it. I would hate for you to follow only my steps and break something.
Good Luck!