Virgin Mobile S5 constantly freezing and restarting after system update.

My wife's phone is a virgin mobile s5. It was only about 3 months old.
It was already on 5.0 when she purchased it.

After doing a system update, my wife's phone became unstable.
Phone will randomly freeze or sometimes makes a crackling sound
then restarts.

Any of this didn't happen at all before the update.

Any help would be appreciated