If you normally use your netbook with an external monitor and find when you are disconnected the built-in screen won't come on ...
... check to see if the laptop has set the brightness down to 0 (no backlight) by hitting function+[brightness up]. Works from the BIOS screen (mash f2 after bootup from a full power off), probably will work from booted OS too.
(logged for posterity - hope this helps someone)
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