You may already know to use the power button to power on, power off and reboot Galaxy S9 or S9+.
But occasionally, the power button may be not working as expected. You may have to use button (key) combinations to power off, power on or restart Galaxy S9 or S9+.
This Galaxy S9 guide explains how to reboot, power on and power off Galaxy S9 and S9+ in both normal situations and abnormal situations (e.g. when Galaxy S9 or S9+ hangs.).
Please note, in this guide, we do not differ reboot and restart. They are used interchangeably.
Why do you need to reboot Galaxy S9 or S9+ periodically?
You may know you have to reboot Galaxy S9 when you update the phone (for example, updating Galaxy S9 or S9+ to Android Pie). In this case, some system files being used have to be replaced. Therefore, you need to “stop” the system, then restart the system with the updated files.
For apps, normally, it is not necessary to reboot Galaxy S9 if you update them. Apps in Android are running in its own container. The system can destroy the container and then reload the app with updated apps on Galaxy S9 or S9+. Therefore rebooting Galaxy S9 or S9+ is generally not required for updating apps on the phone.
But some tech guys may tell you to reboot Galaxy S9 or S9+ periodically (from once a month to once a week, NOT daily) to make the phone more responsive.
This is actually a valid suggestion.
When you reboot Galaxy S9 or S9+, all app leftovers (some apps sometimes may fail to clean up their own files after you close them) and ghost processes will be cleaned.
How to automatically reboot Galaxy S9 or S9+?
Samsung added the feature of “auto restart” feature in Galaxy S9 and S9+.
You can enable auto restart on Galaxy S9 and S9+ in Settings — General management — Reset— Auto Restart.
As shown in the screenshots below, you can enable auto restart so that Galaxy S9 or S9+ will be rebooted automatically within one hour of the specified time.
You can only set the schedule as once a week only. Frequently restarting/rebooting Galaxy S9 and S9+ will not be helpful.
The safest way to power off or reboot Galaxy S9 or S9+ is using the power button options.
If you press and hold the Galaxy S9 power button for more than 2 seconds (but less than 7 seconds), you should see the power button options as shown below.
You can tap the Power off button to power off Galaxy S9 or S9+. Some airlines may ask you to power off the phone during take-off and landing.
If you tap the hold (long tap) the power off button, you will then get the option to reboot into safe mode as explained in this guide.
To reboot Galaxy S9 or S9+, you simply tap the Restart button.
The power button options menu is available at all times unless the Galaxy S9 or S9+ hangs.
So you can use the power menu in Galaxy S9 lock screen. But you will be asked to unlock the phone before you can power off or restart the phone. This is a security feature, not a bug.
Update: after updating Galaxy S9 or S9+ to Android Pie, you can add the lockdown mode to the power menu. Please refer to this guide on how to use the lockdown mode on Galaxy S9 and S9+ with Android Pie update.
How to reboot Galaxy S9 and S9+ if the Galaxy S9 hangs?
Occasionally, Galaxy S9 or S9+ may hang due to some apps or operations, and therefore, the phone is not responsive.
In this case, you will not be able to get the power button options. Sometimes, you cannot even turn off the screen.
When Galaxy S9 or S9+ hangs, you cannot remove and re-insert the battery to power off and reboot the phone because the battery in Galaxy S9 and S9+ is not removable.
So, you can use the following two methods to reboot Galaxy S9 or S9+ when the phone hangs.
When Galaxy S9 or S9+ hangs, you can hold the power button for more than 15 seconds to see whether the phone restarts or not.
If method 1 is not working, you can then try to hold the volume down button, then hold the power button without releasing the volume down button (holding 2 buttons in total) for 15-20 seconds.
This button combination is a hardware level implementation equivalent to pulling out and reinserting the battery. So, it should work in most cases.
If method 2 does not work either, you may try the following button combinations:
- Hold volume down + volume up + power buttons (3 buttons) for more than 20 seconds.
- Hold volume down + Bixby + power buttons for more than 20 seconds.
- Hold volume up + Bixby +power buttons for more than 20 seconds.
What should I do if I cannot power on Galaxy S9 or S9+?
Normally, you can power on Galaxy S9 or S9+ by holding the power button for a few seconds.
If you cannot power on Galaxy S9 or S9+ with this method, you may try:
- Check whether the battery was fully drained by connecting the phone to a charger. If the red LED indicator light turns red, it usually means the battery is OK. You need to charge the battery for at least a few minutes before you can power on Galaxy S9 and S9+.
- Hold volume down + power buttons for more than 7 seconds to see whether Galaxy S9 or S9+ powers up.
- Hold volume up + Bixby +power buttons for more than 20 seconds to see whether Galaxy S9 can boot into recovery mode.
- Hold volume down + Bixby +power buttons for more than 20 seconds to see whether Galaxy S9 can boot into download mode.
Please note, when you need to hold more than one button, you should always hold the power button as the last one.
You may refer to Galaxy S9 and S9+ layout page on the location of the physical buttons on Galaxy S9 and S9+. Especially, do not confuse the Bixby button with the power button or volume keys.
Do you know how to reboot Galaxy S9 and S9+? Can you power off and power on Galaxy S9 and S9+?
If you have any questions or encounter any problem when you try to power on, power off or reboot Galaxy S9 and S9+, please let us know them in the comment box below.
The community will help you find the answer.
For the user guide for new features of Samsung Galaxy S9 and S9+, please check Galaxy S9 new features guides page.
For using Galaxy S9 and S9+, please check Galaxy S9 how-to guides page.
For using Galaxy S9 camera, please check Galaxy S9 camera guides page.
For accessories for Galaxy S9 and S9+, please check Galaxy S9 accessories guides page.
For the official Samsung Galaxy S9 and S9+ user guides (in PDF format), please check Galaxy S9 user guides page.
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