Usually when a specific zone shorts out the timer it's the solenoid on the valve. Either that or the ground and the hot wire are touching somewhere along the line on that numbered zone. Try this. Disconnect one of the wires at the valve which is shorting out the timer. Then turn on the timer. If it doesn't short out then you know it's the solenoid. If it does then the short is somewhere along the wiring. Good luck!
If I can't fix it, it's broken!