LG G3 uicc unlock not working

[KD73]

I just bought this used LG g3 that's on Sprint. Since it already had it's contract paid off I can uicc unlock it. I know what it means. But when I start the unlock, it says there was an authentication error. Someone help.

 

[Rukbat]

First, was the Google account removed from it when you bought it? If it had a Google account, you have to put your google account on it and remove the original one - and you'll need that account's password to do that.

Second, either the unlock code is incorrect (don't keep trying - you have a fixed [and not that large] number of tries before the phone locks and is useless), or there's a problem with the firmware. And most of Sprint's phones of that age (it's almost 4 years old) weren't SIM-locked to begin with. Besides, since you can't use it on Verizon, and you can't use it on any GSM carrier, why would you need to unlock it even if it were SIM-locked to Sprint?

 

[KD73]

I use cricket not Sprint. But I had the previous owner call sprint, and they unlocked it. But thanks for your help!