1 The first possibility is that the network data is not fluent, small is recommended best in the network signal good place to upgrade. or download the firmware directly using WiFi.
2 The second possibility of an update failure is that the battery does not have enough electricity. The last small series of mobile phone is so, the power is not enough, update the process of unlimited restart, so the update must ensure that the battery power enough.
3 There are some small partners after root, also can not be updated. If you are sure you want to update, you can restore the factory settings first, and then download the firmware upgrade again!
4 The last possibility is that we are too impatient! It takes a certain amount of time to update the system. We need to wait patiently. In addition to update the time will not press the other button on the phone!
Warm tip: To update the system before the preservation of good data yo! Lest the data be lost after the update.