broken screen in restore factory boot

[eithan]

Hi Im trying to boot my laptob with a broken screen using a secondary monitor but when i boot up it comes on the monitor and then loses signal, how can i keep the signal as i cant see how to continue with the factory settings set up ?

 

[das_stig]

May be an option in the bios to select external screen as default output device.

I don't think using the keyboard switch Fn+F4 or similar will work.