How can I make an unlocked phone (previously Verizon) work with Cricket Wireless?

[Garrison Stephens]

Hello, I just bought a third party unlocked Note 3 from Groupon. It was originally a Verizon phone. That being said, it is not allowing me to update my software to the latest version of Android. It says the service is temporarily unavailable, I suppose it's because it needs the Verizon towers to update. How can I update my phone? Also, because of it's Verizon history, it can only receive 3G speeds on my carrier, Cricket Wireless. Can you help please? I love this phone and don't want to return it (I have 30 days to return) Thanks in advance!