This is exactly my situation, down to the 27% and rooting history. I am still with AT&T though, so straightalk probably doesn't matter.
Every couple of days now the phone demands its update be attempted again, and it again fails.
I HAD the same issue. I WAS rooted took the NI1 OTA and was then unrooted, so I thought. Tried the NJ4 OTA and it stopped at 27%.
WARNING!! I'm a N00b to the best of my memory this is what I did all this info is available at XDA forums! You better backup ALL your data FIRST!
Since I do not have a high enough post count here I can not provide links to the files
Downloaded Oden 3.9 and installed It has been updated to 3.10.
Downloaded ALL_ATT_I337UCUFNB1_I337ATTFNB1_505595_REV06_user_low_ship_MULTI_CERT.tar.rar
Downloaded SAMSUNG_USB_Driver_for_Mobile_Phones_v1.5.45.0.exe and installed (From Samsung support)
Opened the box the S4 came in and took the USB cable out connected cable to PC USB port (make sure you use factory cable)
Ran Oden 3.9
Used AP option in Oden to load up the .tar file above you don't need to extract anything from the RAR file just leave it as is!
Put the S4 in download mode (Vol down, Menu and Power)
Connected USB to S4
Pressed vol up to continue
Started Oden flash
Got PASSED
Let phone just sit for 15 minutes after re-boot
Powered off then on
Setup phone again
Then took the NJ4 OTA with success!