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.

Press and hold the power button for 10 seconds and see if your Mac starts up.

For MacBooks, verify that you are using the correct power adapter with your laptop–check the information guide that came with your MacBook.

If available, try another power cable/adapter and see if the cable is the problem.

Make sure the outlet works by plugging in something else and testing it.

Check that the power cord and the adapter are making a snug connection to your computer and wall outlet.

Mac Won’t Turn On At All? If your Mac doesn’t even turn on, let alone boot up, let’s check a few things

Upgrading to macOS High Sierra? What You Should Know.

macOS Could Not Be Installed, How To Fix.

PSA: macOS Catalina will kill your 32-bit apps - here’s what you should know.

How-To Factory Reset MacBook Air and other macs with macOS.

How to use Finder in macOS Catalina to Sync and Restore iPhone If your MacBook or other Mac does not start up at all after macOS High Sierra/Sierra update and hangs on a gray screen with an Apple Logo, here are some steps to consider: Related Articles

The majority of these problems are usually related to third-party software running on your MacBook. 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.

Macbook pro 2013 update