Hi @suhnate ,
Here is a link to the ifixit JBL Flip 3 Repair guide.
You need to open the device and check for any damage and corrosion caused by the water.
To clean away any remaining moisture and corrosion to the pcb and the other components use a Q-Tip moistened with IPA 90%+ (Isopropyl Alcohol - available from most pharmacies/drug stores/chemist shops etc). Do not use rubbing alcohol as it is not as effective as most are <70% IPA and can contain scents etc. If you have no choice, then check the label for added ingredients and %.
Here is a link that may be of some help.
Electronics Water Damage
Splashproof does not mean waterproof ;-)