I recently accidentally cut my sprinkler system control wire (the black wire that has many colors of small wires in it) between control panel in garage and the green valve box inground. After I reconnected the wire (matching color wires) and turned on manual operation of sprinkler for a while, the water was gushing out from the backflow preventer's relief valve. The backflow preventer model is Febco rp 825Y.

Does anyone have any experience in this? The sprinker was working fine before the wire cut. Now even if I turn off the sprinker control panel, and turn on sprinkler water line, water will immediately gush out of the bottom relief valve of backflow preventer.

Is this a symptom of a broken backflow preventer? Or it's something else wrong with the irrigation system pipes/valves and the backflow preventer simply doing its job to prevent water from going backward into the main line? Could this be because of the wire cut/reconnect that damaged either the backflow preventer or the irrigation valves?

Thanks in advance for any suggestions.