I need some help with my PS3 anybody know about this?

OK, I have the first gen PS3. It didn't crash or I don't think it did, ill explain. I have owned this for as long as they have been out, I got one of the first systems delivered to walmart. I never had any problems out of it, until now. I was playing GTA 4 and the game for the first time (froze). So I reset the system as I would with any other game when it freezes. After resetting it, I pushed the on button and it came on and froze at the main screen. I knew something was wrong at this time. I pressed the button again to power the system off, it took every bit of 20 seconds for it to Finlay power down. I left it off for about an hour, I turned it back on and it did not freeze, I figured, OK good it was just overheated. I turned it back on and I put in MW2, it was on the loading screen of Modern Warfare 2 and it froze again. I powered the system off and left it, I took the system apart hoping to find that there was a way to fix it that way. I unplugged and took the system all apart piece by piece, I put it back together and it loaded Modern Warfare 2 fine and played it for about 10 / 15 minutes... It froze again. Now the system will not even show a picture. I called SONY and the guy said I needed to send it in for (servicing). I asked how much money I was looking at. By the time he got done he was at $346.00.... I asked him why it was so much money, he replied, because you took it apart... ?.?.?.?.?.?.?.?.OK..... And he also attempted to tell me that it was IMPOSSIBLE to take a PS3 apart without the (Special Tool!) I said dude that's not a special tool, its called a star tip. Haha I thought that was funny. But I need to know this, if it is impossible to fix this, I understand. I just saw no need to spend more money than the system was worth. Any help will be much appreciated!!! Thanks