Hi Andy, thanks for your time. I tried just having the AC adapter and battery removed + holding the power button. When I do that, the mac try then to start (without sucess) but the fan are blowing at maximum speed for 3 seconds and then switching off. The power button is working. I also tried to start the mac without keyboard but directly by shorting the two contacts on the logic board. The mac also tried to start and shut down (the fan are blowing only 3 seconds). The 2 fuses seems ok, I checked with controller. I am more and more afraid that the logic board is gone away. The full story is that I was working on a document thursday morning, then I moved home and wanted to continue to work but the mac did nt manage to get awake ... I forced a shutdown (pwr button for some seconds) and voila ! I check the voltage on the cable from the left I/O to the motherboard : around 12.5 V. Is this ok ? I don't know anymore what and where to look for. Any idea ? Regards.

Hi, thanks for your explanation. I'm facing the same issue and i removed the logic board and left IO board to check for bad component but without success (I tried different RAM module in both slot) Now, I have only the left I/O board + logic board with 1gb RAM in front of me. Everything else is unplugged. - with battery (full charged) it's not starting - with magsafe neither but the battery is charging (orange led on the magsafe + battery led blinking) I really would like to know if the logic board OR the left I/O board is dead. Is the logic board + left IO + 1gb ram enough to start and test the logic board ? or do i need to plug something else ? thanks in advance for any tips. PS : tomorrow, i ll check the power output ...