I have a HP Pavillion 500-236d desktop pc. It was working fine for me for 7 years since 2013. I upgraded it by adding extra 4GB ram, GTX1050ti graphics card, replaced the original hdd to ssd and added an aditiobal 4TB hdd. Few days ago, I accidentally switch off the power supply, extension plug, and turn it back ON after my TV cable started sparking because it was not inserted properly. So my pc didnt immediately turn ON, it took some time but turned ON in 1 hour, but after i plugged all the cables it didnt turn ON, and even removing back all the cables it didnt turn ON. So I check my computer power supply 24 pin with my multimeter, and it was good except the 24pin port on my motherboard didnt work anymore. My question is will my PC be back as normal after replacing with a similar model motherboard? I mean if i do that i dont have to reinstall windows right?

If its motherboard problem, advisable to reinstall windows, even if its the same motherboard. xD

So I have to buy a new windows 10 product key and install right? I cant use the existing product key right?

Can use existing key. But you need to know whats the key, if you dont, then need to buy new key.. xD

Okay Thank You so much for replying me 🤩👌

You're welcome bro. and good luck