On a Mac laptop:
If you have gotten this far without a successful boot, try resetting the SMC on your MacBook Pro. Unplug the laptop from the charger and peripherals. Hold down Shift + Control + Option and the power button for ten seconds. Let go of all keys and reconnect the charger.
Hold the sleep/wake and volume-down buttons at the same time. Press the sleep/wake and home buttons simultaneously for at least ten seconds, until the Apple logo comes up on the screen. After performing the reset on any model, plug your phone in for half an hour to an hour, and see if it responds.
Ensure your Mac is plugged into a power source. Try swapping out the charger or power cable, or using a different power outlet. The charger itself may be damaged. If you're using a MacBook and its battery is completely dead, you may need to wait a few moments after plugging it in before turning it on.
Plug In The iPad And Let It Charge For Some Minutes A dead battery could be the reason why your iPad is not turning on, even when plugged in. Failing batteries display a “low battery” indicator but a completely dead battery does not respond until there is enough power to allow it to function.
Make sure that the AC adaptor option is chosen (instead of battery). Look under the options panel and ensure "Restart After a Power Failure" isn't checked. I have a feeling that's your problem. Also, always ensure you plug in the AC adapter into the wall outlet BEFORE you plug it into your MacBook.
Shut down your computer first, then unplug it completely. Wait for 15 seconds before putting the cord back into an outlet. After you plug the Mac back in, wait 5 more seconds and then turn on your Mac. If you have an Apple silicon Mac, just restart your computer and the SMC will reset.
The quick fix: This could be a simple system crash. Perform an iPhone 7 soft reset even if the phone seems dead. To do this press and hold BOTH the power (sleep/wake) button and the volume down button at the same time for 10-15 seconds. If the logo appears - your forced restart did the trick.
If your laptop won't power on, even when it's plugged in could have a faulty power supply, battery, motherboard, video card or RAM. When troubleshooting a laptop that won't start, begin with the basics. Ensure the plug to the power cord is plugged into an outlet and to the computer.
This can happen for a few reasons: Your computer temporarily paused charging to extend the life of your battery. Your battery may drain to 90% or lower before it begins charging again. If you have an Intel-based Mac, you can turn off battery health management in Energy Saver preferences to immediately resume charging.
Check the Power Source Take a small common item like a lamp or a clock and try to plug it into the same outlet and see if it turns on. If it doesn't, there's a good chance the outlet is bad. If it does, it could be a bad MacBook charger. You can also simply take your charging plug and move it to a different location.
Your computer performs best when connected to AC power. It can use the full output of the Power Adapter AND when doing especially challenging work will also freely "borrow" power from the battery. In some cases, even with the power adapter connected, the charged state may even decline during stressful work.
How to fix a MacBook won't turn on issue
Here's what to do if your Mac won't turn on:
Open System Preferences and navigate to the Energy Saver settings to confirm that: Turn display off after is not set to Never. Prevent computer from sleeping automatically when the display is off is not checked. Wake for network access is not checked.
You might find that your MacBook USB-C port is loose or that dirt is clogging up the port. Either of these issues could explain why your MacBook isn't charging when plugged in. Power off your MacBook and carefully clean your USB-C port or MagSafe charging adapter using a dry brush to try to fix it.