This problem can also be caused by hardware damage. Your phone or tablet may not be powering on because it’s broken. But, if there’s a software problem, the steps here will fix it.
Charge Your Phone or Tablet For a Few MinutesIf your Android device’s battery is almost dead, you’ll often see an “empty battery” indicator on the screen when you try to turn it on. But, if you let the battery completely die, your phone or tablet won’t respond at all when you press the Power button.
To fix this problem, just plug your Android phone or tablet into a wall charger and let it charge. You can’t just plug it in and try to turn it on immediately — you’ll need to give it a few minutes to charge first.
Plug it in and let it charge for fifteen minutes or so. Come back later and try to power it on with the Power button. If the problem was caused by a dead battery, it should boot up normally.
If it doesn’t work at all, try plugging the device in with a different cable and charger. The charger or cable could be broken and preventing an otherwise-good device from charging.
Pull the Battery or Long-Press the Power ButtonLike other operating systems, Android can sometimes hard-freeze and refuse to respond. If Android is completely frozen, your device may be powered on and running — but the screen won’t turn on because the operating system is frozen and not responding to button presses.
You’ll need to perform a “hard reset,” also known as a “power cycle,” to fix these types of freezes. This cuts the power to your phone or tablet entirely, forcing it to shut down and boot back up.
On a phone or tablet with a removable battery, you can remove the battery, wait about ten seconds, and then plug the battery back in and boot it up.
On a phone or tablet without a removable battery — that includes most modern Android devices — you’ll need to long-press the Power button. Press your device’s Power button and hold it down. You should only have to hold the Power button down for ten seconds, but you may have to hold it down for thirty seconds or longer. This will cut the power to your phone or tablet and force it to boot back up, fixing any hard freezes.
Perform a Factory Reset From Recovery ModeIn some cases, your phone or tablet might begin booting, but the Android operating system might crash or freeze immediately.
To fix this, Android can boot straight to a recovery mode menu, where you can perform a factory reset. If your device is booting up before freezing or experiencing other serious problems, use recovery mode to perform a factory reset.
To do this, you’ll first need to power down your phone or tablet and then boot it up by holding down several buttons at the same time. The exact combination of buttons you need depends on your device. Perform a web search for the name of your device and “recovery mode” to find the buttons it needs. For example, the Samsung Galaxy S6 requires you to hold Volume Up + Home + Power.
Restore Your Device’s FirmwareIf your device’s software is damaged, the factory reset process might not work. You may need to restore the Android operating system from an image provided by your device manufacturer. For example, this may occur if you’ve been messing around with custom ROMs or otherwise performing low-level tweaks to the system software.
Depending on the device you have and its manufacturer, this can be easy or hard. For example, Google provides easily installable firmware images, which you can install manually. For other devices, search the web for the name of your device and “reinstall firmware” to find instructions. If you’re lucky, the manufacturer will give you an easy way to do this.
Android also has a hidden “safe mode” you can boot into, which works just like Safe Mode on Windows. In safe mode, Android won’t load any third-party software, only system software.
On some devices, you can only boot into safe mode from the phone while it’s already running. On other devices, you may be able to press a certain button while the phone is booting to have it boot into safe mode. Perform a web search for the name of your device and “safe mode” if you want to try using safe mode. This will only work if some sort of third-party application is freezing your device after it boots. This normally shouldn’t be possible, but it could happen.
Image Credit: Karlis Dambrans on Flickr, Karlis Dambrans on Flickr, Karlis Dambrans on Flickr