Hunter sprinkler controller shows "no ac"?

The Verizon cable guy was here and he disconnected power to sprinkler controller for few hours but then when re-powered, it displayed "no ac". In some online forums they say the controller is not getting the power. How is it showing "no ac" message without the power? This display goes blank when... show more The Verizon cable guy was here and he disconnected power to sprinkler controller for few hours but then when re-powered, it displayed "no ac". In some online forums they say the controller is not getting the power. How is it showing "no ac" message without the power? This display goes blank when power is disconnected.

Also, I can change all other settings without any problem but only when set to "automatic" it says "no ac". I tried resetting the controller and it did work for one night and watered my lawn but by morning it went back to "no ac". I opened the controller cover and could see some connector for 9v batteries but no batteries. Any clue?
Update: The Verizon guy installed FiOS box in the garage and used the same power outlet to power FiOS box. I am using an extension to power FiOS box and sprinkler controller from the same outlet.
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