Multimeter the wires in the garage to indicate which 2 are not working. Find those valves with a valve locator like a
progressive 521. Once you understand where the valves are you will get a better understanding of a bad wire
connection or cut wires.
You may need to hire a pro. If they don't have a 521 and a multimeter you don't want them in your yard for this project.
Good luck.
If you are near Houston give me a shout!