I would take the battery out. The problem usually isn't the water itself, it's what's in the water that causes problems. Sugar, salt/minerals. If it has a sim card, that should be OK and can be read by another phone (that uses a sim card). You might also want to consider rinsing the whole phone in distilled water (then dry it out with rice) because that will rinse out the impurities. Distilled water isn't very conductive but the impurities are and when they dry out inside the phone, they can short things out when the battery is put back in.