Mobile Data Connection Error LTE: ESM-27 EMM-x

A little over a month ago I purchase a refurbished Samsung Galaxy S6 from a local Cricket store. A few days ago I had found out that the phone was rooted, which wasn't allowing me to use several different apps including the Samsung Pay. Last night my phone had shut off and wouldn't turn back on, as well it said "Custom Binary blocked by frp lock. After doing some research I had attempted to fix it myself, first I downloaded something called Odin and a CDMA file from Samfirmware. upon factory resetting my phone I had found out that my phone no longer had internet connection. I've tried everything from resetting my APN to default, restarting my phone, factory resetting my phone once again. Please help me solve this problem. I just want an unrooted phone.