About a month ago we replaced the fan switch in our bathroom with a Lexicon 30 min timer. About 10 days later I noticed that it would not turn off. We replaced the switch with an identical one, as the guy at HD said it was likely just defective. Today I discovered that the timer will not turn on and the little green light is off. The fan is 0.7 amps. The box holds the fan switch as well as switches for the shower and vanity lights. The lights are working. What is causing this problem?