Thanks for the question.
So you have already had the 6 digit radio code convertered to the 4 digit unlock code?
Yes, use the hour and min buttons to get the display to 0311, then press the AM/FM button to enter the code, then the display should show "SEC". I have never seen a code "10P" come up. I have seen INOP come on the screen when the code was entered incorrectly too many times.
If it does not say LOC, LOCKED, or CODE, then it is probably INOP. The code cannot be entered in wrong more than 7 or 8 times, and if it is, then the radio will show INOP and be locked down.
What you will need to do to get the screen back to the LOC display it leave the key ON for 1 hour, no less, or until the display says LOC. After that, enter the code in and the radio should unlock.
If you do this, make sure all lights, ac controls, etc are off so the battery does not die, or put the battery on a charger.
If you can give me the 6 digits you got from your radio, I can check to make sure they are correct.
1st: Hold HR button to enter the first 2 digits
2nd: Press MIN button to set the second 2 digits.
3rd: Press AM/FM
That is correct.
You are welcome, please let me know if you need any other help on this.