I have a 1999 Acura TL, which intermittently would not start, especially after sitting in the heat or for a long period. Tonight, I changed the battery and now the battery indicator came on (not on with old battery installed). Additionally, I attempted to input the security code for the radio, but evidently got it wrong on the first attempt, and radio shut down. Typically, it would say wrong code and I could reenter, but this time turned off and remains so. I unhooked and rehooked battery in an attempt to reset but no result. ANY IDEAS?

Did you have the old and new batteries tested to see what the voltage is? You may have burned out the alternator if you drove the vehicle too long with a weak battery.

Is the radio aftermarket or stock?