Chosen Solution
Black screen of death, but I can see the screen when I shine a flashlight through it and it works with an external display. The keyboard backlight is still working, but not the screen. I haven’t had any spills or drops, but this has happened before. It magically fixed itself last time and lasted for another year. It seems I’ve run out of luck. I’ve reset the SMP, PRAM, and all of that, and I had an Apple person look at it. They said it wasn’t the display cable, but they’d have to send it in. I’m thinking it might be the inverter system (screen, inverter, inverter cable, board) based on some googling I’ve done. What do I need to do to test this? Where is the inverter cable/board?
The inverter cable/board is nowhere in your Mac. Latest laptop using that technology was manufactured by Apple over 10 years ago. Backlight is created by a complex circuit on the logic board and it can’t be troubleshooted without professional skills and tools. The best you can get with a DIY approach is a logic board replacement or you’ll have to find someone into component level repairs. https://www.ifixit.com/Store/Mac/MacBook…
@jeccahelp besides the great answer by @arbaman you can always consider learning more about your board and how to possibly diagnose the fault. Since your keyboard backlight still works you know that at least the LED backlight driver is still working. So, all you would need to do is to post some good pictures of both sides of the logic board as well as give us the 820-xxxx number printed on your board. For a repair you will need to use tools like a multimeter, soldering stations etc. as well as having the skills for using it. I’d be looking at pin one (1)on the LCD connector since that is a common trouble spot. Use these guides to work on it. MacBook Pro 13" Retina Display Mid 2014 Repair
