My friend borrowed my samsung s4 device while overseas and unlocked it to use over there. However, ever since he got back, whenever I put in my sim it gives me the error of unregistered sim and does not give me cellular coverage. The sim is working fine on another phone. I tried manually looking up the mobile networks from the connection and found Koodo listed there, however it gives me an error "Unable to connect to Koodo". System update does not work either. I would appreciate any help that would get the sim working on my current S4 without having to change the phone. (my friend says the overseas worked perfectly fine on the device, the error is with the Koodo sim in Canada). The device was issued by Koodo as well.