There are two ways to do this usually and you almost got one of them right I believe. The battery removal trick does work, but you probably want to leave the battery out for at least half an hour. It takes a while for the system to use the residual power.
The other way that is available on most motherboards (sorry don't know about Sonys) is that they have a CMOS reset jumper. With those you simple move a jumper over two pins, restart the computer (which clears the CMOS), shut off the computer, take off the jumper, and reboot like normal. If your system supports such a thing, it is probably listed somewhere in your motherboard manual.
Get your facts first, and then you can distort them as much as you please. - Mark Twain