I am also facing same problem After installing the update, the android logo came and it says wait for 30 minute for update after this my device automatically restart, and the update was cancel
Try performing a system repair using PC Companion as this will often fix issues - This will factory reset your phone
Switch off your phone and unplug from Pc (Hold volume up and power for around 10 seconds) Start PC Companion and select Support zone then Update my phone/tablet then in Blue Repair my phone/tablet and follow the on screen instructions - When prompted connect your phone still switched off holding volume down or back button - This should start the repair or reformat process
If you are using Windows 8/8.1 or a 64bit operating system then adjust the settings for PC Companion and run in compatibility mode and chose Windows 7 or XP
