Chosen Solution
I use my laptop mostly with external display via displayport, but laptop always in open state(use internal monitor also). No water or drop damage – on half of working day internal monitor became black but external continue working. I try reset/boot macbook with keyboards shortcuts but with no success, so probably hardware problem. I use flashlight to check display and i can see that display working. In most cases to which part of display(or whole display) this issue could be related from your experience, and from which point i need to start ? UPDATED: i can see interface if i use flashlight. Thank you!
If you can see the desktop icons using a flashlight that tells us your backlight logic on the main logic board is having problems. You either have a burnt fuse link or the WLED driver. The WLED driver is not something a DIY can do. It might be best to find someone who does board level repair near you.
