Chosen Solution
Spilled tea (no sugar!) on my girlfriends Macbook last night. Took it apart today and cleaned everything with first 70% then 99% isopropanol. There was very minor corrosion in a few spots, notably the screen connector. Today managed to get it to boot and backup in time machine (she had no backup!) However the screen is very dim, I needed to use a headlamp to read it and even so it is difficult. There was one similar thread (Liquid spill results in extremely dim screen, how to fix?) with no conclusion. I understand some macbooks have a fuse for the screen? Is this the case with the A1377 model and where is it?
The FET is never the problem, don’t go shorting things without knowing what is going on. Do you get 8v, 0v, or 27v at pins 3 and 4 of the LCD connector? Issue can be full 27v is there but a burned out screen, 8v is there unboosted, or nothing is there at all. Common issues are burned feedback via to LED driver, blown fuse, burned BKL_EN resistors, shorted cap on boost line. Also measure for a short to ground on backlight output. No guessing and no shorting is allowed here, only measuring, analyzing, and learning prior to fixing the REAL problem!
chris, the fuse is reference designator F9800 and is a 2AMP-32V 0402-HF. All you have to do, is to check the fuse for continuity. The LED driver is right next to it, and that can most certainly give you problems as well. Once we have your serial number we can hopefully identify the logic board number and get you more details of the schematic. Hope this helps, good luck.
Update Thatnks for the serial number. It allowed me to verify that this is the right fuse. The driver next to it, is reference designator Q9806 and it is a FDC638APZ SBMS001 Mosfet P-Type RDS(ON)43 mOhm @4.5V and LOADING 0.4A. You can get it from here if needed. I would suggest that you get the datasheet and measure that FET first.
