I'm new to macs so please bear with me. I recently bought an early 2008 15" macbook pro running OS 10.7.? on craigslist. It worked fine for the first month but now it will not boot, and when I say not boot, I mean nothing. I press the power button and I hear it start up for a few seconds and then nothing. No start up screen, no chime/tone, no power button/keyboard backlight, nothing. The SIL is lit and will get brighter as I close the display, but other than that, nothing. The bottom will also get warm so I know something is running to generate the heat. My first thought was that it was the nvidia display problem but I'm now I think it's a boot problem and/or sleep problem. On the rare occasion when it does boot, it works fine but if I leave it for awhile (with display closed) it shuts down (I have turned off sleep mode for battery and power source) and then it won't reboot. I do not have any startup, boot or recovery disks. I've tried resetting the SMC and PRAM but that doesn't do anything. I've tried booting into safe mode and that doesn't do anything either. No keyboard combination at boot seems to do anything, so I don't even think that the OS is starting up. I have an apple store near me so I can take it there if needed but I thought I would try to fix it myself first. Any help is appreciated. Thanks. PS I know there are a lot of boot threads here but most seem to have their problems after the OS has loaded and I don't think I'm even getting to that point. If there is another thread that addresses my problem, please point me in that direction.