Visual inspection
WARNING: This page is about a different car, the 2008 Suzuki Grand Vitara, 2007 Suzuki Grand Vitara, and 2006 Suzuki Grand Vitara. However, it is still accessible from the selected car via links, so may be relevant.
Check for obvious damage, such as cracked or broken case or cover, that could permit loss of electrolyte.
If obvious damage is noted, replace battery. Determine cause of damage and correct as needed.