I had upgraded my iPhone5C from iOS8.2 to 8.3 over the weekend because I wanted to do to a restore. So I had to upgrade.
After the upgrade and restore, I could use the phone for about a day or so until this afternoon it suddenly went into a black screen. I couldn't turn it back on at first. After a few hours later, I could finally turn it on again, but it got stuck in a restart loop at the Apple logo. It keeps restarting on its own and never gets pass the Apple logo into the Home screen.
I got it into DFU and did a restore. I kept getting an Unknown Error 14 at first until I suddenly was just able to get through the error at one of my tries and restored it. But after the restore process, the phone goes back to its restart loop again.
I didn't have any problems with the phone before the upgrade in iOS. What could have had happened and how can I resolve this issue?