Pc hiccups

Hi I am requesting help for an issue I can’t really look up properly. It’s kind of a puzzle. I recently updated to a 4090 on my older 9900K Aorus Master setup and I bought a new PSU with the newer 4090 ready Corsair PSU but for some reason my rig had problems booting up until I reset the mobo...

Today I decided to do a little cleaning, so I went and used compressed air to clear the dust in my PC. After connecting it back up it started up normally so I stepped away for a bit. When I came back the PC was turned off and I couldn't start it and there was a faint smell as if something has...