The radio asks for its anti-theft security code.
You should have the code somewhere in the radio's manual.
Depending on your model, the radio goes into the SAFE mode either after disconnecting power or when using a panel from another radio.
Code Entry as Follows:
Turn Off Stereo
Switch On Ignition (No Need To Start Engine)
Press & Hold Preset " AS " and
Switch Radio On - Display Shows
" SAFE " And Then Shows " 10 - - - - "
Press preset " 1 " repeatedly for 1st Digit
Press preset " 2 " repeatedly for 2nd Digit
Press preset " 3 " repeatedly for 3rd Digit
Press preset " 4 " repeatedly for 4th Digit
If the correct code number is now shown
Press & Hold Preset " AS " Until the Unit Beeps
A.R.S., December 2012