The mod bios which functions well is created by the automatic tool. And I update the bios rst modules with UBU to 17.5.3.4203.
Unfortunately ,the mod bios still can not be entered. Maybe my operation is wrong, but I can not find out yet. Or the B250 chip is not suitable for the bios modules. Thank you anyway.
My computer: Gigabyte B250m-HD3， I3-9100f cpu