Why does my phone crash after locking after update 5.1.1?

[danny1234321]

I have a Samsung galaxy s5 mini and my phone updated to 5.1.1 but ever since this update when my phone is locked and left for about 30 seconds it seems to crash and I have to remove the battery to reload my phone. There is no way to unlock my phone after this crash as I have tried pressing the lock key, holding the lock key, pressing the home key, holding the home key, holding the lock and home key together. My phone also cannot receive calls when this has happened. Any help?

 

[VigneshB]

Tried a factory data reset?