i put my MBP (intel santa-rosa late 2007/early 2008) to sleep by closing the lid. i went back and opened the lid and got nothing apart from hearing the optical drive make its usual noise. so i killed the power and tried to boot up normally... again nothing other than optical drive noise and the white light is on at the front of the MBP. have tried resetting the SMC - still nothing tried CMD-OPT-P-R during boot - still nothing. tried swapping out RAM - still nothing. i get no bong, no display at all. only indication that MBP is actually getting power is the optical drive noise and the white light. battery also still charges whilst plugged into mains. any advise please ?