I have an '05 TL and I guessed too many times on my radio code input screen and now the navi screen won't ask me to enter the code. I have since found the code but I'm not being asked to enter it anymore. I've already tried disconnecting the battery but it still won't prompt me.

 

Try holding 1 and 6 down and wait for the serial number to pop up, then turn the radio off, then on again.

I don't know your answer, I'm just guessing here.