Chosen Solution
I just got a mid-2008 A1260 Macbook Pro 2.5ghz 15", and when I turn it on, the sleep indicator light glows like normal, then stays glowing, but dim. The screen stays black and there is no boot chime. You can hear the Superdrive and hard drive spin up like normal, and the fan runs quietly, but nothing else happens. I already tried different combinations of the RAM cards, and have ruled that out as a problem. I have tried PRAM reset (command+option+P+R) multiple times and nothing happens (could be the keyboard, who knows). I have tried booting it to my flash drive with an OS X 10.7 installer and that made no difference. What else could be wrong? I can’t seem to figure this one out.
Sorry to say you’ll need a new logic board as the combo GeForce 8600M GT GPU/North Bridge logic chip is likely gone. Keep in mind this is a very old system and parts are hard to come by
