Not being able to turn off the alarm is a strange decision, especially since the sound is sooo loud and annoying, who even came up with that? If safety alarms in airplanes can be muted, why not for a water pump in consumer products?
Anyway, I dissasembled the whole thing, including the 2 electronic boards and I did find indeed moisture, right between the bottom board and the plastic housing. Therefore I could wipe it clean and dry everything and I didn't need to wait 24h. I imagine that it was triggering the alarm when I was putting the lid on just because it was slightly heavier and the board would have touched the water.
Unfortunately the whole design is not ideal, the way it's built any drop of water that might spill from the tank will invariably end up there. I would have thought that electronics sitting under a lot of water all the time would be a bit more water tight.It's also very difficult to just check and see, and then you have to wait 24h or some undeterminate amount of time, hoping it all dries up, instead of having an easy way of opening and cleaning, which could solve the issue in 10 mins.
Just my two cents.