Sorry to hear that. Sounds like you need to be a little harder on yourself and don't make that sort of mistake next time.
As for your bad GPU, I have only had one out of at least 20 in my lifetime go bad back in 2001 after about 2-3 months of use, I believe it was a Nvidia Geforce Go 5200. Back then I didn't overclock but I also didn't pay attention to temps. Today I have pushed cards to their limits but only while exercising caution and they come back asking for more. Reason I mention this is you may have given up a little too quickly since I have run into situations where it required a card to be moved into a different slot initially or even taken out several times then put back in and or motherboard bios reset several times. Sometimes it's the sequence that you do things in, which is a result of poor programming of one or both bios's I usually assume. I would also suggest having some spare components around. At the very least an extra power supply but preferably a second working order PC to swap components out with for testing...there have been many times I would have given up a GPU or ram ect for dead if not for a working reference setup to swap the part into in and a few hours of diligence.
If money is tight you can always bestbuy the suspected component and return for a full refund once it's been eliminated from possible issues.