13" aluminum unibody, 2.0 or 2.4 GHz Core 2 Duo processor.

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Replaced Logic board and dead fan... won't start up

I posted previously in another post about my macbook that wouldn't power up. I ordered a new logic board and installed it this afternoon. I was in the middle of installing snow leopard when the computer shut down. Long story short, I found the fan was dead. I replaced with one from another computer. I now can't get 2 seconds past the apple logo. What could be the problem?

I've tried starting with the battery out and with it in. Trying different ram from other computers I know are good. Nothing.

UPDATE...

I booted in safe mode. I got all the way to the login screen. The keyboard wouldn't type, and the computer shut down. I had to hold the shift key down all the way to the login screen. Thanks in advance.

Answer this question I have this problem too

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Will the unit boot OK from the original system installation disk or a retail Snow Leopard disk?

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It sounds like the laptop is still overheating. Either the heat sink overheated and went bad or the board overheated and caused an issue with one of the BGA chips. Try cooling the board with some other sort of fan and see if it runs any longer. If this does not work you can try to preheat the chip. This is something that we do to determine if a BGA is bad. heat the chip up with a hair dryer or heat gun and do not go over 175C. In doing this you are trying to heat the connectors under the chip not the chip itself. You are also not trying to reflow the connections at this point this is just a test. Put it back together quickly and see if it stays on for longer. I would also cross your fingers that the heat sink is bad and not the logic board

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Do I use the hair dryer with the board upside down? Taking it apart takes 45 minutes. Putting it back together takes a little less. I could just buy a new heat sink.

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I really think its the heat sink. i got another fan and put it in. IT would only run on low and not ramp up speed when it got hot.

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but did it shut down quickly as it was doing before or would it stay running?

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answering everyone here. It shut down after the apple logo and the pinwheel spin. I got it in safe mode almost to the desktop, but as soon as I let the shift key go, it shut down.

I couldn't get it from the original disk. I don't have it. The seller didn't provide it.

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luke will be eternally grateful.
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