KevinSee

After the laptop fell into sleep mode and wake up again. Now both external monitor and laptop screen are working fine. That's interesting.

Issue: Whenever I plug in the HDMI cable into the laptop, the laptop built-in screen will become black screen. However the external monitor is working fine. I tried mirror mode and standard mode (extended display) and both will result in black screen for the built-in laptop screen. I need to restart the laptop in order to get the built-in screen to be working again - without plugging in the HDMI cable. Once I plug in the HDMI cable, then it will become black screen again. Even I have unplugged the HDMI cable from the laptop, the black screen on the built-in monitor remains. Here is the link to the EFI: https://github.com/skevin83/Hackintosh-Dell-E7470 The EFI folder size exceeded the maximum allowed to be uploaded here. Thus I put it in GitHub. Specification Dell Latitude E7470 Laptop INTEL CORE I5-6300U 12GB DDR4 RAM 2133MHZ 256GB SSD STORAGE M.2 INTEL HD GRAPHICS 520 14" INCH HD 1366x768 I performed a fresh installation of Catalina then upgrade to Big Sur. Thanks. IORegistryExplorerResult.zip