Advice, please!! Plugged in a 4 pin connector and PC would not turn on...

Hey guys, So I just got a new case and while checking is everything was plugged in and working properly(it was) I saw a little 4 pin plug and I thought it for my fans. I plugged it into my CHA_FAN and my pc wouldn’t turn on so I unplugged them and my pc was turned on fine. Then I tried plugging it in while my pc was on and it turned off and now the PB_PWR light keeps flashing and i'm not getting anything. I have a asus rog strix 365-f