This sounds like the water solenoid valve is stuck in the open position or is not seating correctly. The valves are usually spring loaded to the closed position, so if they fail they will fail in the safe mode. I have had dealings twice with Triton and found them very helpful. I have had an ivory shower for about 10 years now, but I do not know the type number. I am therefore assuming that the valve in your shower is removable. If you have the original installation paperwork, it may give you the exact part number but otherwise contact Triton and tell them what you want.
I will not have to remind you that all work should be undertaken with the electicity switched OFF. Also, take great care regarding water leaks inside the shower itself. Water and electricity do not mix. You will obviously have to judge if you feel confident enough to carry out the repair. A new shower may be the best bet.
Bright spark, September 2008