Getting this serviced and fixed rather than replace the quartz movement.
If you send the watch to Omega for service, you may get a new movement as well. The caliber 1538 had at least 4 versions (A, B, C, and D). It is my understanding that if your movement is not the latest revision D, then Omega will (may?) replace it with a revision D to bring it up to specification.
You can ask not to replace the movement. But with the water damage, serviced can't be avoided and lots of parts will be changed ; for the good in that case... 😉