I have no experience with this but I'll try to help.
Try this:
Turn on or restart the computer. Press F10 while the
F10 = ROM Based Setup message is displayed in the
lower-left corner of the screen.
Select File menu.
Select System Information
View specification information about the
processor, memory and cache size, and
system ROM.
In this thread, post what you find there concerning ROM.
If still nothing happens when you press F10 then someone else will have to help. That's all I know to try.