Don't turn the solenoid if it is an older valve.....what a mess you will make with the old style non-internal bleed solenoids.
Use the bleed screw if it has one ..... turn the water off....turn the timer on.....wait 2 minutes....does the solenoid get hot? If so, probly not a bad solenoid. Usually a bad solenoid trips the timer/breaks the fuse etc.....bad wiring does nothing....bad diaphragm will not let the valve open but the solenoid will work...make sense?
To clear it up:
If the valve will come on manually with the bleed screw..and the solenoid is good..the diaphragm probably has pin holes or small cracks in it and the guts should be changed.
If the valve does not come on at all with the bleed screw and the solenoid is good...the diaphragm has huge holes in it or is completely broken....
Sprinkler Solutions, Inc.
Arizona and Colorado
www.sprinklersolutions.net