Did you follow these instructions?:
https://update.kia.com/US/EN/updateGuide
Did you log in as a "guest"?
Is your USB drive newly formatted correctly (exFAT)?
Is it a good/tested USB drive?
Did you copy the files to the very top of the USB drive directory? No other files or folders are stored on it?
If you can't transfer the files, then it sounds like an issue with your USB flash drive. Try a new one?
