Galaxy grand 2 sm g7102 error in installing and stuck on recovery rebooting

Hi guys. I'm seriously new with this. My brother's phone was having a problem with WA's update at first. So, I thought that we need to update the OS. So, we did and we're stuck with the screen showing 'Installing system update>95%>Error!' then this 'Recovery booting' repeatedly. Even right now and we can't even access it. :( Please help.