A Mac that won’t turn on is a whole different situation, as opposed to a Mac that won’t start up. If your problem is the latter, it means that you’ll be able to see something on your screen, or hear your device making a sound, be it a fan or other noise.
1. Before we dive into the more complex solution to this issue, we suggest you first try disconnecting all accessories you have plugged in on your Mac and then try starting up the device without them.
2. If that doesn’t work, then you have to boot your Mac in Safe Mode. This way, your device will run particular diagnostics, in order to isolate the problem. It will also repair directory-related issues and verify the startup disc. When booted in Safe Mode, Mac OS will start with the bare minimum of software that is required to run diagnostics of your startup disk and perform the necessary repairs.
Here we explain in detail How to boot a Mac in Safe Mode. After that, you need to restart your device normally.
3. It is also possible that your drive may be corrupted. In this case, your Mac can boot, but the operating system will be unable to load up. You can fix this by using Disk Utility in Recovery Mode.
Here we explain in detail How to fix a corrupted disk on Mac using Disk Utility.
4. Another thing you can try is to boot via Recovery mode.
Here we explain in detail How to boot a Mac in Recovery Mode.
If the problem still persists, the solution might not be as simple. For further assistance, we suggest that you turn to the Apple support team and/or seek warranty services.