Galaxy S4 won't allow software 2update because of "Custom" Status

[AC Question]

I bought a Galaxy S4 I337M from ebay. I'm trying to update to the lastest software (I have 4.2.2). It won't let me because my Device Status is "Custom". I removed the SD card and restarted the phone. No luck. I even did a factory reset and wiped everything from my phone (I had been using it for a week before I decided to check for an update. I don't know why. Ugh!). It STILL shows up as custom after a factory reset and the SD card still out of it. I used the Root Checker app and it says that I do not have root access. I'm scratching my head. The only reason I knew to do the things mentioned above is from Googling. I don't know my way around other than that. Please help!

 

[UJ95x]

Try to boot into download mode. (Hold volume down + power + home). If it's custom status there it's because the previous owner rooted the phone and didn't reset the flash counter.

Sent from my Galaxy S4 running SOKP 4.4.2