Help installing system update

i have samsung galaxy core prime while i was connected to the internet it was download the samsung update when it completed downloading update i reboot but after few times of rebooting it show ... and again reboot INSTALLING SYSTEM UPDATE and reach up 92% it tell error i have been continuosly trying to get to factory reset mode but that option also doesnt show directly installing system update comes... i have already tried the vol up power key and home buttom combination but it has no effect ... could you please help me