Ya it most likely sounds like a controller problem. Usually with a short in the system or a bad solenoid, the controller with display either "fuse" or "open" depending on the model. With the problem you have, it sounds like its toast. How long have you had the controller for? Sometimes this is the result of a lightning strike or just a defective clock. The RD-900 has been around for some time so it could just be time for a replacement..
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