Macbook Pro Dead & Thermal Sensor issue

Processor 2,4 GHz Intel Core i7

Memory 8 GB 1600 MHz DDR3

Videocard NVIDIA GeForce GT 650M 1024 MB
OSX 10.8.5

I have some strange problem with my 1,5 year old macbook pro.

My Macbook turned one time completely dead when i was doing a dj set. Also it did not charge the battery (so no light with adapter connected)! The space was quite warm and humid. After 3 hours it turned magically on again. After that no issues.

Last month i was in Panama close to the beach. I was working on my macbook with no problem. Closed it, (battery was 89% charged) did not turn it off so put it in sleep. 24 hours later i want to turn it on and was completely dead! Again also not charging battery so nothing. Next days tried but no sign of life. So i gave up. Then after 5 days it turned magically on?! Next day i went back home and since then it works all fine!?

Now I have been to the local Apple store and they have detected a problem with one of my Thermal Sensors. They run some stress tests and after 4 times the macbook turned off. Although with a normal standard test, of the Thermal Sensor, it looks all fine. So the guy at Genius bar said one of the Thermal Sensors is probably oversensitive or not working well.

What they advise me now is to change the motherboard costs €400,-, since is out of the one year warranty! Or just leave it like this since it's working fine. But now i have a total not reliable machine! Think this is crazy. Its definitely some factory defect, Thermal Sensor is too sensitive, or not working well. I'v read more ppl have had these problems with pretty new macbook pro's.