Hi all,
I had similar problems (Macbook Pro 2007): the Mac would start but no display. The behavior was random but got to the point that I just could not turn it on. The blanket trick did not work for me - it did not get hot enough or shut down. Apple repair told me to bet a new motherboard. I might as well get a new MacBook. So after it failed again I thought I can't lose much. I need to keep for a few weeks till I am back in Canada where a new one is cheaper than in Europe.So I cooked it in the oven: 90 degrees Celsius for one hour (including heat-up time. I had to use kitchen gloves to get it out. I let it cool off a bit but not enough - too hot to start. I let it cool down completely and voila, it's working again. I don't know how long that will last but I already shut it down once and it came back up which it did not do before.
Word of caution: 90 degrees for one hour may nave been too much.My keyboard melted a bit: the keys look a bit funny and the space bar is not as reliable as before. But it now looks a bit more exotic and I am typing this message on my Macbook-that's progress!
It's just a shame that the Apple product did not last longer than 5 years. Some of my old Dells still work after 10 years - but I also hate them....
So I will get another MacBook Pro and hope I won't get another NVIDIA lemon.
Good luck cooking your own MacBook, Wolfgang