Chosen Solution
Hello, I have a MacBook Pro A1502 EMC 2835. The screen was shattered so I replaced the entire screen upper assembly. When I replaced the screen, I made the mistake of not unplugging the battery connection from the motherboard. Once I was done with the repair. I turned the computer on, the screen was working and it showed the battery dead logo. So I grabbed a charger and plugged it in. Then the screen would not light up. I did the flashlight into the apple trick on the back of the computer and the screen does in fact work but no backlight. I bought and replaced the backlight fuse. I tested the old fuse and it was not blown but I replaced it with a new fuse anyway. The backlight still does not work. I checked again and I did order the correct screen. What else is there to check? What could I have possibly damaged by not unplugging the battery other than the fuse? I see in other questions here that it may be the LED Driver, where exactly is this located? I have another laptop I can switch the screens with to eliminate the screen from the equation. What do you recommend? Thank you in advance.
From what I can see your issue is still a fuse problem. The image of the fuse appears not be connected on one end.
Double check or replace with another fuse
@deyth okay so your connector actually looks pretty good. Check on pin 12 so. Looks odd (not connected to the backlight) but could just be the light. Here is the location of the LED driver
It is a LP8548B1SQ_-04 and available at multiple sources. I recommend to resolder your fuse after that measure the voltage on pin 1 on your (EDP)display connector. #1 from the top down on your picture. Since this is a life test you want to make sure that you are not touching other contacts. Let us know what you find out. There are multiple other components that could have been affected (hence the multiple edits of this answer:-)but let’s do the easy ones first.
