Hi,
Make sure the system is powered down with the power plug removed. With the case open I would touch the chassis first then remove the card screw and reset the video card edge by simply pulling straight out then pushing gently back in. Then try to power on. If this solves your issue then you can continue. But I would power back down and remove the video card so you can clean the edge connector correctly. You can use 20# paper in one inch wide strips soaked with alcohol (I use denatured but isopropyl alcohol will suffice), lap the strip so the paper covers both sides then pull in one direction. Dispose of strip after one wipe then repeat using a new strip. You can clean the motherboard connector with a old credit card using a folded soaked paper then gently push this into the connector. Use caution and not force it, each insertion, you should use a new strip of paper. If you have any canned air, then blow out the connector before you do the wipes.
Insert the video card and secure then power on to check things out.
Hope this helps.
Have fun & enjoy!