Well, I'd say there's a good chance that you're one of the "rare things" that in my experience really isn't all that rare at all. More often than not, if there is an issue with power distribution due to a faulty power jack or AC adapter, or something else that causes a short circuit or spike in internal voltage, it's not uncommon for multiple components to be affected. Also, if the GPU was damaged by exceeding thermal limits, it's equally possible for the CPU to have been damaged as well.
It's also quite possible that the GPU fried due to a lack of cooling from a fan failure. Are you hearing ANY fans come on when you attempt to power up? Does you unit have more than one internal fan, as in, one for the CPU and a separate fan for the GPU? If so, are they both coming on at boot like they should normally do? If there is a fan or fans that are not working it could easily result in thermal damage to the GPU or CPU and if the fan has failed completely and no reference signal indicating RPM is being received by the BIOS then it's likely it won't allow the system to boot. Many systems, desktops and laptops both, wont' boot at all if no fan reference signal is detected within the first second or less of power state management.
It's equally possible that there is an issue with the motherboard's PCI circuit, which if a short circuit condition occurs or exists, could easily damage CPUs, GPUs, and other devices that communicate over the PCI bus.