tcampbell34
Member
Hello. I have a 820-00281 board that I purchased from eBay. The computer was fully functional except for the touchbar did not work and it would crash and reboot when the computer would go to sleep. I figured out the touch bar was not working due to U4404 and replaced it and the touchbar was working again and it was no longer crashing either. Since this board was fully working now, I decided to try and put the board in another A1707 casing I had to test the screen and other items on the casing but when I hooked everything up and plugged in the adapter, I heard a small pop noise and could smell burnt plastic so I quickly unplugged the charger. Turns out the screen I plugged in had some minor liquid damage to the connector on the LCD assembly that I did not see and so it destroyed U9850. When I took off the heat sink I could see a blow out on the surface of U9850. I replaced it with a new one and connected the board to the original casing with the good screen, and the internal display now turns on again and displays an apple logo, but it only loads about halfway and then the image disappears from the screen but the backlight remains on. This board has some really weird symptoms now. It fully boots to the OS but the image will not stay when I boot normally. If I turn it on with an external monitor connected, the image on the internal screen works fine and so does the external monitor. If I unplug the external monitor while the computer is running, the image on the internal screen stays on for about 5 seconds and then the image goes away again, but backlight remains on. If I boot into safe boot, the internal screen works fine without the external monitor connected. The screen also works fine if I boot into Recovery mode or apple diagnostics so I am not sure where to go from here. I tried a new LCD flex cable also and still have the same issue. I also tried booting into a test OS from a USB stick and same issue occurs when the OS loads. Could it be a bad U9850 that I used or did I destroy something else?
