So glad I was pointed to this site. My MBP was totally dead, and although I was sure that it was the faulty NVIDIA chip, the machine wouldn't boot for the Apple Store genius to run a diagnostic on. There was no chime, no fans ramping up, just a dim light, and a little hard drive chatter. I tried the heat-up method 2 times... I wrapped it in a fleece blanket, and laid a pillow on top, plugged in & upside down. The 1st time it didn't get very hot even after 90 minutes, and the 2nd time it turned itself off. But the 3rd time was the charm, it got quite hot. That was the ticket! I let it cool briefly, and it booted right up just like it used to, with a perfectly functioning display. Now it's back to the Apple Store to get the diagnostic test. Fingers crossed. Thanks!