1. If you don't turn it off and clean the water in time, maybe the signal cable has been water damaged.
2. Remove the signal cable and reinstall it, test whether it is normal or not.
3. You can tear it down and check whether the signal cable is loosen or not.
4. If the methods above can’t fix the signal problem, then you should turn to the hardware solution: change a new signal cable. We have provided [https://www.youtube.com/watch?v=FcywlWxO-Qs&t=48s|how to replace the Moto G5s Plus signal cable repair guide] for you.