HELP HP Pavilion Upgrade Problems!

First off I guess I'll mention that my computer is an HP Pavilion a6342p, here's a link to the specs:
http://h20000.www2.hp.com/bizsupport/TechSupport/Docume...

Okay so I'll try to make a long-ish story short:
I wanted to upgrade my graphics card for better light gaming on my computer (later found out my computer doesn't even have a graphics card), so after researching (or attempting to research) I purchased a Radeon 6670 and an RX-530SS power supply to go with it.
After installing my 2 new parts, my computer wouldn't turn on, the power light would only turn on for a fraction of a second, and then go off.
After trying and trying with no success, I took out the graphics card, and put back the original 250W power supply, and when I tried to start up my computer, I got the same result: the power button would light up for a fraction of a second and then go off.
After trying to find an answer for a couple days now, I've been told it could be alot of things, but what I've seen/been told the most is that I could've possibly shorted out my motherboard.
Hopefully one of you experts on here can identify the problem for me, until then, I will be stuck using an even older computer than the one I "broke."
Help, I am noob.


edit: I apologize for posting the same thread twice, the firs time I posted from the small box on the right side of the screen, and for some reason I thought that one didn't post to the real forums, and the bigger box would post to the forums. Sorry again