If your device is frozen and unresponsive, press and hold the Power button and the Volume button down simultaneously for more than 7 seconds to restart it.

If after restarting the device you still find your device freezes sometimes or is sometimes unresponsive, there are some actions you can try to help correct this symptom:

1Create memory space.2Check for software updates for your device.3Check your device in “Safe mode”.4Perform a Factory data reset of the device. Before performing the factory data reset, remember to make backup copies of all important data stored in the device.After that you can flash your phone manually with Odin. You can find latest Samsung firmware on different sites like samdb.org and others