Make sure the phone is charged and keep trying over and over.
It will work eventually.
Phone: Samsung Galaxy Note 3 (4G-LTE | N9005) @ 2.3Ghz - Jet Black
Memory: 32GB with NO Ext-Memory
ROM: Personal S5 Build (UK CSC)
ROOT: Yes - Knox 0x1
TouchWiz: S5 TouchWiz UX - Android KitKat (4.4.2)
Phone: Samsung Galaxy S3 I-9300 @ 1.4Ghz
ROM: Stock BTU (4.3 - rooted)
Phone: Samsung Galaxy SL I9003 RETIRED
I will NOT answer to questions asking for help by PM unless I ask you specifically to PM me.