Is there a command where a timer starts is the user answers a question incorrectly?

I am creating a program, where the user guesses the password and if they get it wrong, I want to start a timer saying computer will self destruct in 5, 4, 3, 2, 1. But right now, the timer goes off even if you put the correct password in. Is there a way to make it only go off if you get the password wrong?