mobile

My phone kept saying there was an update available, but it would always stop at 28%. I have rooted my phone before, so I tried to use Odin to update to Kit Kat from Jelly Bean. Big mistake. Now my phone won't boot. It turns black at the Samsung screen and still plays the AT&T sound. I tried using Odin to load the original firmware but Odin gave me an error. I tried to do recovery mode, but it said something about not being able to mount. I can still get to the download mode so I'm hoping thats a good sign. Please help if you can.