Hi,
So basically it starts and goes to startup menu.
If you turn off the PC by holding the power button, turn on PC and repeatedly press the ESC key does the startup menu appear?
I am thinking does the keyboard function? (Could you try an external keyboard)
From the startup menu can you enter diagnostics by pressing F2 key?
I woul probable also remove the Hard Drive initially and try reseating the RAM modules.
Are any leds blinking?
Let me know,
David