Phone [Q] LG G2 Lost all 3G/4G

Ok so a guy I work with ( older gentleman ) has an LG G2. He said yesterday he took it out of his pocket and he saw a dead android icon and the screen was black with some words on it. He freaked out I guess and restarted it or who knows what. But now when he boots it, it was completely wiped of all data and the 4G is gone.
I've messed with it for about 30 minutes and tried a bunch of different things to restore it, nothing except when I switch to just CDMA mode it goes to a 3G that is pretty slow.
I was wondering if I go through the trouble of rooting, adding a recovery and resetting the modem with a stock based rom and all of that, would it fix this issue? If anything he will have a cooler more up to date firmware

So what do you all think?