The car got jump started the other day, and it reset all the electronics. I guessed the code (which was wrong), and now its not letting me enter the code again, (which I have the real one, now). How can I reset the radio so it shows the word 'CODE' again?

I've tried disconnecting the terminals on the battery, but it still didn't work. It resets the clock but not the radio.

From the workshop manual.

'If the code is entered incorrectly 3 times, a delay period is activated. The delay period increases every time an incorrect code is entered.
(I)The ignition should be left in the Accessories position to clear the delay period'

So basically you'll have to leave it alone until it resets itself.