First back to all type data like photos, email, contacts, videos etc because this is factory firmware if don't take backup all then you will lost all type data of above mention.
This flash file tested by me without any error working well, you can use this flash file when your device hang on logo problem, restarting problem, security lock problem, password lock problem, pattern lock problem etc software related problem and you can use this tutorial without any box and this is free for all who know about software in mobile, impotent for flashing first must check your micro usb cable if not good then you can't flash it so check micro usb cable second check your device battery that is impotent for flashing if your device battery low so stop your device between flash so this is impotent for flash, before you flash save your data like contact, photos, videos etc because this is factory flash file so you can't save after full flash so must remember all are impotent notes.
2. Extract to both winrar file into desktop or as you like path (must installed winrar software in your computer or laptop)
6. Press and hold Volume Up button and insert usb cable (device key or micro usb cable must be working well)
7. Wait until driver install, if driver installed in your computer or laptop then downloading start automatically in your device