1.Press and hold the volume down and power buttons until the "Android System Recovery" screen appears.
2.Use the volume keys to browse, and then use the power key to select.
3.Choose to wipe cache partition and allow completion.
4.The device should restart automatically, if it does not restart, please select the restart option.
In most cases, this solves the black screen problem. This usually indicates that an application is causing stability issues. In this case, please start troubleshooting the application by disabling or uninstalling the application until the device is operating normally again.
Factory reset can fix the black screen problem
If the previous step did not work, the only other way to fix the black screen after turning on the Android device is to restore the factory settings. This will erase all personal data on the device, so it should only be used as a last resort and back up your data if possible.
1.Turn off the power to the device.
2.Press and hold the volume down and power buttons until the "Android System Recovery" screen appears.
3.Use the volume keys to browse, and then use the power key to select.
4.Select clear data/restore factory settings and confirm.
5.The device should restart automatically, otherwise please select the restart option.
If the second fails, it is probably a hardware problem and you should contact your provider.