My Galaxy S5 cellular network isn't working after I installed new ROM?!?

[AC Question]

Okay so first my phone was having some issues with cutting off randomly (pretty sure its a battery issue now) but I tried to install the stock rom for my tmobile galaxy s5 and everything worked execpt now my service doesn't work at all!!! Please help, do I need to install a new radio for it and if so how do I do that??