The ultimate Mac repair guide: Get your Mac powered on and starting up
The Mac is one of the most reliable PCs you can buy, which is probably why there’s a heightened sense of anxiety when you press the power button and nothing happens. But take a deep breath. When your Mac won’t start, there are a number of reasons why, and most likely, it’s an easy fix. Apple has a support document with advice on what to do when your Mac won’t turn on, but we’re going to give you a little more detail and a few more things to check. So be sure to bookmark this page for when it inevitably happens again.
Before we start, let this be a lesson to keep a backup. Whether you use a cloud service, store important files on iCloud Drive, or use Time Machine with an external drive, you’ll want to make sure your most personal stuff that isn’t already in a cloud—local documents, files, movies, music, etc. That way even if you need to wipe your Mac and start over,
Your Mac won’t power up
If you press the power button and nothing happens, it might actually already be on. It sounds silly, but when the battery lies the Mac goes into a hibernation mode and it can be tough to tell if it’s actually on or not. Listen for fan noise (though even Macs with fans are pretty quiet when they aren’t doing anything), and check for light indicators, such as the backlighting on a MacBook keyboard or the Touch Bar on a MacBook Pro.