
For non-removable battery models: Go to Apple Menu > Shut Down (if needed), once shut down press these 3 keys shift+control+option from the left side of your keyboard, then press and hold the power button along with these 3 keys.For removable battery models: remove the battery, press and hold power for 5 seconds, reinstall the battery and power up to test.Reset your Mac’s SMC (System Management Controller).Third-party RAM often causes these power issues If you recently upgraded your Mac’s RAM, remove the new modules (replace back with original if needed) and test if the Mac starts up.Disconnect all accessories excluding mouse/keyboard and try turning your Mac on.For MacBooks, when booting up press the trackpad–if it clicks, then there is likely a display problem.Verify it isn’t a display issue by disconnecting the display (if possible) and pressing the power button–if you hear any sounds like a startup chime, fan or drive sounds, or see any LED indicators, the problem is likely your display.For MacBooks, disconnect/remove the battery (if possible) then plug in the charger and see if it powers up.Some readers tell us that holding these three keys: fn+ctrl+CMD plus the power button worked for them.



At AppleToolbox have seen these issues with almost every major macOS or OS X release. Some users report that their MacBooks and other Macs will not start after macOS update to macOS Mojave, High Sierra, or older macOS Sierra. Is your Mac not booting up after the latest macOS update? Or seeing a white, gray, or other Mac screen of death? If so, don’t panic! You’re not alone.
