What is the issue with my speaker?

Hello, my father has an old JBL Charge 3 that has served us well over the years (6? 5 years probably?) but now it sounds extremely bassy when producing a sound and music is almost unrecognizable. My dad said that it started doing that after it fell in the water (though this model is water-resistant, so I am not sure if that is the case). My assumption was that there is something wrong with the speaker part of the device, as all electronics seem to function. What do you think the issue is?