Chosen Solution
My macbook started acting erratically, apparently from liquid damage, and I ended up replacing the logic board. After putting everything back together the laptop worked fine for maybe ~15 minutes and then the screen went black. It doesn’t appear to be a backlight issue - I can’t see anything on the screen with a flashlight. It still works on an external display via hdmi. I tried resetting the smc and pram/nvram as described here and other similar answers: How to reset the SMC, PRAM and NVRAM on a Mac Laptop This didn’t seem to help. So at this point I reopened the back, disconnected the battery, disconnected the display cable, reconnected the display cable and reconnected the battery. When I turned it back on, the display was working again. This time it continued to work for a couple of hours, but again the display just suddenly turned black. Any ideas what might be causing this and what can be done to fix it? Update (12/20/2022) An update: this time i just disconnected and reconnected the battery, did not touch the display cable, and the screen came back to life…
Liquid damage is always tricky! I’m suspecting you also got the display wet as well. In this case the lower edge as the is where the T-CON logic is. You’ll need to take the display off following this guide MacBook Pro 13" Retina Display Early 2015 Display Assembly Replacement The carefully remove the black clutch cover to expose the logic held within it. To help you review this MacBook Pro Retina Display Teardown while there as some minor differences to your system it’s basically the same. Once you have access to the logic board carefully remove the display cable so you can inspect it and the logic board for corrosion damage. Sometimes cleaning things up is all that’s needed. Otherwise it’s time for a new display assembly.
