If there is no electricity and you are still having water flow through the vavles, you have a hydraulic problem. I would schedule some time on a saturday to bceome one with your sprinkler system and change the valves. just cut em out and put in some new ones. Get the right kind of PVC cutter from a sprinkler supply house not a Home depot. Get some wire nuts, hot PVC cement, some slip Valves, some quick repair couplings, some 1" couplings, some one inch 90's, T's, and a good angle shovel trench style 2" or 3". It can be fun if you are saving 125.00 per valve and gaining knowledge and experience too. It will still cost you some coin.
PVC can be known to cut your hands, so be carefull.