I have a gigabyte b450M DS3HIf you don't have any video and the USB is not functional, then your PC isn't powering up.
What motherboard do you have?
Ok I’ll try those out, and my case luckily came with a one of the speakersThat board has nothing to help diagnose your problem. No LEDs or anything. You could get a motherboard speaker and connect it to the pins on the front panel connector to get a beep. That might help you diagnose.
Start with the basics. Power connectors plugged in completely. Front panel correct. CPU fan plugged in. If those all checkout then you have to go deeper. I would probably pull the motherboard out of the case and bench test it -- http://thenerdbench.blogspot.com/p/bench-testing.html