Logic board or left I/O board problem?
My MacBook Pro has been through %$#&. A long time ago I dropped it, cracking the screen. Since then I have replaced the entire display housing (isight, screen, back cover etc.), and the hard drive. Nearly a year after repairing it the inverter board went bad. The backlight for the screen would not turn on but I could still see the screen if held at the right angle under the right light.
When replacing the inverter board everything else broke. I'm not sure if I accidentally destroyed it with an electro-static discharge or if it was just poor timing. At this point I gave up and bought a new MacBook Pro. Putting the failed one aside for another time.
It has been over a year and I decided to have another try at fixing it since logic boards are now on eBay for around $250. Because it would not charge the battery I started by buying a new left I/O board, when that didn't fix the problem I ordered a new logic board.
I installed both the new left I/O board and the new logic board but I am still having trouble. when I press the power button:
- If the laptop is running on battery then, I hear the Hard drive begin to spin up, make a horrible clicking sound and repeat. The fans make a small jerking motion but do not spin up, the screen stays black and I DO NOT hear the start-up beep.
- If the power cord is plugged in, the hard drive spins up and stays spinning WITHOUT making the clicking sound that is heard on battery. But nothing else improves, the screen does not turn on, the fans make a jerking motion but do not start spinning, and there is no start up beep.
- If the power cord is removed the hard drive continues to spin normally.
- The new I/O Board does charge the battery.
Connecting a DVI cord has no effect (ruling out a bad screen?).
My question is: How do I know if my problem is related to a bad logic board or a bad left I/O board? Is there any way I can test each piece to prove which one is defective?