BIOS Flashback LED flashed first fast and slowly and finally turns off

[Affengeiler]

Hey,
today, I've built my P with the B450-F Gaming II and the 5 5600, but now I have issues with the BIOS Flashback. When I flash the BIOS, the green LED is flashing slowly, then faster, and slowly with no pattern - then after some minutes it just turns off....Anyone who has a idea what to try out? :/ My USB Stick is FAT32 & formatted on MBR.

 

[johnb35]

If you aren't using a supported processor that the original bios supports then you most likely won't get it updated. Did the system boot up before with the cpu installed?