Dead early 2008 MBP, machine didn't start at all, no warranty. Genius couldn't run the diagnosis, couldn't say what was wrong. Genius offered me a $310 flat rate repair, I accepted.
A few days later, the machine returns. Repair report says they replaced the logic board due to a faulty Nvidia GPU, and the cost was $0.
Your experience may vary, there's also a small chance that you actually have a different problem.
Well here's the whole story. I'm sure I had the Nvidia Issue, I got the 310 flat repair done hoping they did the same thing that you say happened to you, no such luck, but what the hell, I was happy to have it working again. Then went on vacations, at the 80 day mark, so when it started malfunctioning I could not take it into service. So when I took it to the genius Bar I was a little pissed that they would not extend the 90 days warranty, nor acknowledge the nvidia issue. And I was not about to spend another 310$!!! ridiculous...
So I baked the logic board, really doubted it would work... But it did! Its amazing!!! from now on I'm baking everything that malfunctions!
So I encourage every one to try it as a last resort!