Question
FU is flashing on the display. What do I need to do to get my system functioning again?

Answer
Probably you lost some characters from the display. It should be FUS and one number. This is caused when the controller detects a short circuit at one of the valves. The number is the valve number. If your display gets damaged, replace the selenoid at valve # 1, if the problem continues replace the # 2 and so on. You can use the same new selenoid. If you are electronic savvy, at the timer check the zones with a multimeter, set it to measure Omhs at 200, Put one lead (red) at the zone # 1 and the black at the COM port (White wire), repeat this step for each zone. The reading should be between 20 and 60 Omhs. The zone (s) where you get a reading less than 20 Omhs is in short. So replace the selenoid. Make sure there is not short circuited wires from the controller to the valves.
Regards
Guillermo