My Samsung Galaxy S3 keeps getting stuck on logo screen. How do I fix my phone?

[Android Central Question]

I have tried to factory reset it and I keep getting this.... Failed to mount / system (invalid argument) #MANNUAL MODE# Applying Multi CSC.... E:failed to mount/ system (invalid argument) Can't mount '/system' (invalid argument) E: failed to mount /system ( invalid argument). My phone was working fine up until a week ago. What can I do to fix it. Frustrated.