AsRock z68 Pro3, problem has occured second time, again after unplugging and plugging PC from power for couple days, BIOS is freezing on Splash Screen and do not allow me to enter UEFI Setup, after first time I gave computer to repair and I was told the problem was one of the BIOS's on motherboard, it was only needed to flash the BIOS, right now I want to do it on my own but I don't know how to do it, I've done bootable USB and installed on it BIOS update from AsRock website but nothing happens when it turns on, please give me instructions how to flash the BIOS.