Q: Are from one of the Slavic countries where you need to smack the hardware to make it work?
That reminds me my old Russian made CRT TV that i had 20 years ago. It had colors and sound but since it was at the end of it's life, every time i turned it on, there were no sound and image was monochrome. A good smack dead center of the CRT screen and colors were back.
2nd good hit at the top of the TV and sound was back as well.
TV showed colors and produced sound until i turned it off. That continued each time i wanted to watch TV until i got tired of smacking it to work and i replaced it.
Point is: unless you have old Russian (Slavic) made PC that needs the "tough love" to work (which i highly doubt), what you just did was one of the most effective ways to break your PC. Modern PCs are very sensitive to vibrations and i have yet to see a modern PC that would survive the smack at it's PC case.
At this point, and by what you describe (PC not staying on for more than 3 seconds), following or all of them are dead: CPU, MoBo, RAM, GPU.
Unless you don't have 2nd, compatible PC, where to test all those 4 components out, what you're looking towards is effectively a new PC or at the very least, a very expensive repair bill (if you haul your PC to local PC repair store).
Life lesson: modern PCs need gentle love, not tough love.