system
A chat on subreddit /r/pcmasterrace
human
Upgraded from what? Did you verify your MB was 12th Gen. ready when you upgraded? If the bios wasn’t upgraded your PC won’t know what to do with its new brain and won’t even try.

If you did
1) verify everything is plugged up correctly.
2) try shorting the power button manually. Your case button may of broke in the process.
3) re-seat CPU
gpt
12th gen is the first gen for LGA 1700. This advice is misleading. If the CPU fit the socket and is 12th gen the BIOs should not need an upgrade at all. 

This would only be the case with a 13th gen.