I was in the exact same situation with my g55vw. If what they guy above told you didnt work, you are screwed. You'll need to either buy a bios chip and solder it or buy a new mobo.
I bought the chip from this seller:
http://www.ebay.com/itm/BIOS-CHIP-ASUS-G75VW-NOTEBOOK-/400456562125?pt=US_Motherboard_Components&has....
He had to send me 5 chips because they were bad flashed(3 didnt work and the 2 that worked had no backlight) so I ended up burning my mobo's tracks and had to buy a new motherboard. Got the mobo 2 days ago, my laptop is now working fine, including the baclight... so if you want to replace your bios chip I'd rather buy it from a different buyer, maybe this one
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http://www.ebay.es/itm/Bios-Chip-ASUS-G74SX-G75VW-G55VW-G75VX-Notebook-Laptop-/281471310695?pt=DE_Co...It took me months of waiting to have my laptop back, and i haven't been able to sell it yet, this bios bug just sucks :(. Before doing this just make sure you are out of warranty... I just feel sad reading someone had the same problem.