Alright, So I recently just put in a Asus B-450 F Gaming and Ryzen 7 3700X. I discovered it needed a bios update, so I put in my old processor. A Ryzen 5 2400G, flashed the BIOS, reinstalled the Ryzen 7 and to no avail we still have no boot. I tried a suggested fix, to flash, unplug from wall and press power button to release any left over power, unplug motherboard and replace the chip and hook it back up, still didn't work. Any suggestions guys?