Radio Problems and Unlock Codes

1997 Oldsmobile Radio LOC
Radio does not turn on, shoes the letters LOC on display after changing to a new battery.

Need Stereo Unlock Code
What is my radio code when it says LOC in 2000 Chevrolet Silverado 1500. I replaced truck battery now radio wont work.

2003 Chevy Malibu radio, gauges, headlights problems
I removed the factory stereo, replaced it right away, and now the red blinking light on the stereo doesn't blink. The fuel gauge doesn't work, neither does the temp gauge, auto headlights, and I think the ac quit cooling.

2001 Pontiac GP Radio Unlock Code
In 2005, I took my car to get serviced at a Cadillac Dealer. The radio had been unlocked and my 4 digit code was lost.

Need Radio Unlock Code for Buick Century
battery was replaced now he can't get the radio to go back on. He did the code this and came up with the numbers. Can you help with instructions on how to enter the code and also help me find it.