After a quick search, looks like these are your BIOS options/settings : To Enter: F2 To Flash: Windows Base BIOS Installation Boot Option: F12 DMI: Satellite 元50D TSETUP Default Settings: InsydeH20 BIOS (out of the box settings). If you are not prompted, try tapping the F2 key during boot up.
You enter your particular BIOS utility by pressing the F2 key when prompted during the boot process. I too, don't know what you mean by 'locked'.