blazer radio loc out

[chevy130]

I have a 2000 blazer and my radio is on LOC . I have the code, entered it, and still have no radio. Entering the code works as far as getting the clock back on the display but no music, just white noise. Am I doing something wrong ? Does my truck have to be started or just turn the key to ignition on ? Also does the radio have to be off before I enter the code ? With no radio I can't tell if the radio is off or on since you push the volumn button in to turn the radio off & on. Also when the white noise comes on the button for auto tune works(ex: C/W Rock News) and the only way to get rid of the white noise is to pull the fuse which resets the radio back to LOC, pressing the volumn button will not turn it off.