GM radio locked

Purchased radio for 2003 s-10 pickup. It worked when I installed it for a day or so then the LOC came on the dial. No matter which series of buttons I push it will not respond with anything on dial but LOC. The dealers tried and came up with the same. I pull out the wire harness in back of radio and put it back in, the radio works as normal of 10-15 sec. then LOC again. Any ideas what to do. I am not sure if this radio ever can work or I need to do something else. Thanks.

Is this a factory radio or aftermarket ?