Graphics card issue with HP ENVY m7 notebook

[Colleen34]

I have an HP ENVY laptop that I had only for a short while (maybe a year) before the graphics card began to go. I wasn't doing anything intense on it other than maybe playing sims even though in the specs it should have been able to handle that and I never modified the laptop in any way or ever dropped/damaged it. At first when the display started to get weird it had very small rainbow dots that were  mainly visible when the display was black/dark, then it progressed to the screen glitching out and it got progressively worse until it went completely dark and I could no longer use it or get it to work at all no matter how many times I tried to boot it up. I took it in to a repair shop to have it looked at and they told me that the graphics card was shot and not the display/screen because when they connected it to a display both were black meaning it was the card and that it wouldn't be worth it to replace it since it's connected to the motherboard and it would be cheaper to just buy a new laptop. So I bought a new laptop but kept this one on a shelf because I wasn't sure what to do with it and I didn't want to sell it for parts since my data was on it and I didn't know how to erase it completely. Now it's been sitting in my closet for the past year and a half and I just decided to try and boot it up because I was looking to see if I had anything in the disc compartment which won't open unless the laptops on and to my surprise the laptop turned on and I could see the screen. The screen has the little dots like it did when the graphics card was first starting to go and will glitch a little if I try to run/open anything on it but otherwise the whole screen is visible and I can see things/the touch screen works too. I have no idea why this happened because I was told that the graphics card was shot so I'm wondering what happened? Is it possible that somethings loose and has maybe shifted when I moved it or something? I'm just wondering if I can repair it or try to do anything to it before I just give up and wipe it while I can see the screen and try to sell it for parts. Is there anything I can run on it to see what's completely wrong or where to unscrew on the bottom of the laptop and look if anythings out of place. I just find it so hard to believe that a graphics card would go bad on a $1,000 laptop after a year. It was new when I bought it too and not used or refurbished. Thanks