Im on ek02 and I was rooted, tried to update it just stood stuck until i hit menu then gave me and error a few days later i unrooted tried again same thing. I have tried again and again did factory reset same thing I dont understand why.
Did you remove any applications while you were rooted?
If you liked having root I would just flash the EL29 pack here http://forums.androidcentral.com/ep...11-root-e4gt-latest-method-el29-firmware.html
If you want to stay stock flash this [ODIN][STOCK][TAR] SPH-D710.EK02_CL704398 (EK02 Modem/Kernel/ROM - Factory Restore) - xda-developers , use the one that wipes user data and then accept the update again.