I had a similar issue with my Galaxy S4 Mini from US Cellular.
But I was always doing th factory reset from stock recovery only.
I found that I also had to do that factory reset from the stock backup & reset menu too before I got 4G working again.
I'm not sure why you wouldn't do the factory reset from recovery first. Sometime you must do that otherwise you get stuck on the US Cellular splash logo.
Maybe you need to do the factory reset from stock recovery first and then from stock backup & reset menu?