Default [Q] Galaxy S/ on OTA: System UI has Stopped working

HI I ****ed up REALLLL BAD. So, i tried flashing the 4.3 touchwiz launcher of the galaxy s4 (cant post url im still new here) I'll pm if you want

And itried to flash it on my galaxy s3 wich is on Android 4.3(model SGH-I747M) ( the ota update) But nao the system UI wont stop crashing (I know it was stupid from me) ANd I Have no Idea how to fix this
I really need hel.

Would i be able to reflash the stock 4.3 with odin ? Or would it brick my phone ?
Oh and i did a backup with rom manager BUT i moved it to my ext sd card to save it on my pc But now i can't restore it because i have to move it back to mnt shell emulated ... But i cant do it because of the " Systems UI has stop working"
Any ideas?