cpu ryzen

I stole my brothers cpu (my brother no longer uses it) its a ryzen 7 2700x (also it hasnt been touched for like months) and it didt work when i turned it on and took out the cpu to see if it fried or somthing and i dont see anything and i also dont have any thermal paste rn. so is there a way i...

i am planning to buy the b450 pro vdh max with ryzen 5 2600 cpu. i have recently come across some threads discussing issues of backward compatibility in new bios update in MSI motherboards. So, i was wondering whether i will face the same problem with the cpu compatibility with the latest bios...