You enter the code into the shuttle's console just in time. T-minus 15 seconds is called and you make your way back to the time machine and close the door as you hear the countdown reach 3. The time machine comes to life and you manage to escape before the boosters kick in. The screen inside the machine comes to life and you get to see your handiwork in real time, if you want to.
And you are off again. As if changing events in history twice isn't enough, you've still got more to do. But, there is a problem. An alarm is heard, red lights begin to flash and "Error, unknown year" is heard. From a slot in the console of the time machine, a message appears.