Radio CODE

I allowed my battery to drain, causing the radio to display CODE. I _thought_ I knew the code it wanted, and attempted it and a couple of variations, all of which were wrong. Now, I have the code card, but the radio will not accept any entry. I know the code I have is the right one, and I'm certain that I tried too many codes from my memory, and set off some sort of counter. How do I erase the code counter that disables the radio if too many codes are input? My gut instinct is that if I disconnect the battery for a while, it should do the trick. Any thoughts?