Display problem sony vaio

[mmzf]

I'm using vpcw12s1e sony vaio. it's screen is broken now. i attached an external monitor. but it only works when i reach login screen. i want to access the bios. but broken screen can't make me see anything until i reach login screen. please help in details. Thanks

 

[Lutfij]

Follow steps 1 through to 8 in this tutorial.