My laptop screen is working but I can only get the secondary display working when I close the laptop lid after turning on power. I believe external monitor starts up after the windows logo and such so much too late to go to BIOS.
Are you saying that you don't want to use the laptop screen at all?
You are likely to need to change something in the BIOS to allow the secondary monitor to be used as the primary, however you might need to disconnect your external monitor initially, make the relevant change(s) in the BIOS and then reconnect the monitor.
I hth, although maybe a little more clarity on what you are trying to do would be good :)
Also as @barlop says below, can you give us the make / model of your laptop? That would help identify the correct key sequence you may need, if that is the solution :)
I presume your LCD panel on the laptop is broken ? Why else would you try to get into the BIOS on external monitor only...
First: In case the laptop has multiple external monitor outputs: Try them all. It could be that the BIOS is explicitly configured for "LCD+VGA" or for "LCD+DVI" and your monitor is connected to the other plug.
(Windows ignores these settings, so you can get image in Windows itself.)
Boot with the lid closed and external monitor attached.
You should get a picture on the external monitor.
Now reboot and keep the key to get into the BIOS setup pressed as soon as the external monitor goes blank.
With a little luck after a few seconds the BIOS will come up on the external screen. (Even though it doesn't do that on a cold boot.)
In this case you have most likely configured the BIOS to go "LCD only" in stead of "Use BOTH". Windows will ignore that setting, but BIOS will honor it. With some luck the BIOS keeps using the external monitor on reboot after Windows has switched it on.
If that doesn't work either there is one option left: Wipe the BIOS settings on the laptop so it reverts to factory default, which in 99 of a 100 cases is "use all monitors".
Take the battery out of the laptop. Unplug the power-supply.
Open the covers on the bottom. Somewhere you should see a small CR2032 type battery. It is about 25 mm (1 inch) across and about 2-3 millimeter in height. It is usually mounted in a small holder soldered onto the motherboard or is covered in black isolating tape and attached to the laptop by 2 wires (usually read and black).
Remove the battery from the holder (this can take a little force to get it past the retaining clip) or disconnect the 2 wires (they usually have a connector that you can unplug at the motherboard side).
Leave the CR2032 battery out for a couple of minutes and put it back.
This should wipe the custom-settings from the BIOS and have it revert to factory default. This normally restores the ability to show the BIOS screens on a external monitor (if the lid is closed while booting).