My samsung galaxy core 2 got a system update so I installed it. Eventually it kept going to 90% until it said error and then restarted the whole process. It kept doing the same thing get to 90% say error and restart and continue the cycle. I cant even use my phone anymore. Please help me.
Try a factory rest, and install the update again.
How to Enter Recovery Mode on Galaxy Core 2 and how to do a Factory Reset
1) Take your phone and turn it off.
3) Release held keys when the Samsung Logo appears on the screen Then select from Recovery Mode menu "wipe data / factory reset" using Volume buttons to navigate and Power button to confirm.
4) Choose "Yes -- delete all user data" to confirm the whole operation.
5) You can return to Android by selecting “Reboot system now”.
Images used are not mine but are taken from this webpage