Chosen Solution
The MBP in question had a soda spill last September. Finally got the correct logic board and replaced it this afternoon. Plugged it in, let it charge for about 30 minutes and tried to boot. Optical drive did its thing (mechanical noises), it made the happy MBP booting up noise (known in my home as the WALL-E sound), and stopped there. The keyboard backlight works, and the LED at the front right corner is turning on and off slowly. I can see the screen is getting power; it’s still black, but it’s a “powered” black. My question is, is there something else I should be doing? I have seen several references to a PRAM reset and a PMU reset, both of which were alluded to in situations similar to mine. How do I do these things and would they help? I heard the sound and got excited. Now I’m down in the dumps again.
Check your LVDS cable connector. On your MBP model the LVDS cable carries video and power to the LCD backlight. Since you have a new logic board but probably using your old cable it could have been damaged (shorted) by the liquid spill. If you see black spots on the pins, clean them and try the cable. If you still dont have screen lightning then you could have to replace the LVDS cable. Another troubleshooting step would be to power up your machine directly from the logic board after disconnecting the top case from the logic board to check if you still have the lightning issue. If not then the problem is top case related. Liquid spill on a computer can lead to unexpected issues and sometimes many parts can be affected. If the liquid was not directly spilled on the top case then forget the top case inspection.
This could have happened if you originally blew out your lvds cable coming from your lcd display from the original spill so please check the lvds cable to make sure none of the pins on the connector are burnt/black/bent/damaged if so then most likely you blew out the new working logic board with a bad lvds cable from the your old machine, seen it happen way to many times before but if your lucky you may just have to replace a 2amp fuse to get the backlight working again
