Did you check the MD5 to make sure that it downloaded properly? My suggestion would be to download it with a computer, rename it to "update.zip" on a computer, copy it to your internal memory on the phone, and flash it through stock recovery. This should work, what errors do you get when you try to flash it? You're on stock 4.3 when you try to update, correct? In order to flash the OTA you cannot be rooted or have modified the system in any way.
Trust us, this will work.
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