Reasons troubleshoot a MacBook Pro that won't power on:

• Make sure your Mac is turned on.-Let's start by determining whether the issue is that your Mac won't start up or that it won't turn on - the two may sound similar, but there's a significant difference. On your Mac, press the Power button. If you don't hear a startup bell, no fan or drive noise, and no graphics, video, or visuals of any kind appear on your screen, your Mac isn't turning on at all.
• Examine your power supply.-Make sure the Mac is turned on and plugged in properly. Alternatively, if it's a laptop, make sure the battery isn't dead.
• Change the power cable or adapter.-It's possible that the issue is with your computer.
• Examine your display.-This may apply to you if you use a desktop Mac, such as a Mac Pro or Mac mini. You can skip this step if you don't have a separate display connected.
• Safe Boot is the safest way to start your Mac.-Safe Boot restricts which checks and functions your Mac runs during startup, as well as performing some diagnostics.
• PRAM / NVRAM should be reset.
• The SMC should be reset.-In some cases, you may need to reset the SMC on your Mac (System Management Controller).

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