Fixing Nvidia GPU

[Interocitor]

So I have an ASUS GTX 670 DC2 on my hands. I bought it expecting it to be an easy fix but it turns out the previous owner abused it quite a lot. 
The connectors and LEDs show signs of having been in an oven. An electrolytic cap seems to have lifted. Either someone was trying to desolder it or there was some arcing/heat damage. The area surrounding the leads was covered with a hard brown residue (maybe flux). There was no thermal paste between the heat sink and die. Screws were missing. There were no insulators to keep the backplate nuts from scratching the board.
The first thing I did was baking it. Monitored the temperature and used no-clean flux. Put it back together but the screen stayed black.
The next thing I did was inspecting the components. One of the 0805 caps was cracked and measured shorted. I tested the PCIe fuse and it was defective. I scraped the cap of the board and bridged the fuse and now the card boots fine. Before I replace the fuse and put the card in my main PC to test it I want to know a few things:

Why did the fuse blow?
Is the 0805 cap just for bypassing?
What are the symptoms of defective electrolytic caps in graphics cards?
Is there a danger to the motherboard from a graphics card that is known to blow its fuses?

Go easy on me. I'm just just a newbie.

[System Error Message]

please read the OP's post he has already fixed it and wants to know why it happen. my guess would be lightning/surge/bad PSU that failed while the card was in use.