Sun Smart is new GE timer.
http://waterheatertimer.org/GE-timers-and-manuals.html#15312There is no repair for defective timer, except buy another at Home Depot and return defect in new package.
When I bought 15312 timer for testing, I found many packages at Home Depot were taped together as if people returned the timer. The large aluminum fin shows that timer is expected to get warm.
When testing the timer, the door stuck, and the timer seemed cheaply made. Intermatic brand timers are more robust at this time.
The instruction manual is not clearly written as could be, and timer requires a lot of button pushes for each setting.
Because the instruction manual is complex, requiring multiple button
pushes for each setting, I suggest writing out the steps to make sure
nothing is skipped over.
If lights turn on-off with override, then timer should be wired correctly.
Be sure to reset timer before programming.
Press setup button twice to begin programming.
Check programming for conflicts and overlaps that will cause timer not to function as expected.
For example selecting days of week. If program1 ON says turn on at 7:00 pm all days of week, and program1 OFF says off at 9:00 pm Tuesday.
Another point of confusion is Dawn-Dusk-Time. If you want timer to turn ON at 7:00, then select Time.