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.

Galaxy Grand II Duos G7102- Stuck At Samsung Logo

I bought a Samsung Galaxy Grand II Duos G7102 Factory Unlocked International Version Phone - Gold. It worked fine for about a month but when I turn it on it just says Samsung on the screen and will not do anything else. Any ideas on how to reset this phone or what might be wrong with it?

how to go back to stock rom g7102 ?

hey guys,

I want to go back to stock rom as all custom roms have bugs :(

I want the 2 sims work with voice unlike all roms.

or can u recommend a bug free rom instead plz.

I'm on custom rom (( cm-12.1-20150823-UNOFFICIAL-ms013g-ver4_4 ))