DIAGNOSIS The motor is not engaging. The click is the switch or relay activating. This is almost always a dead or faulty battery connection.
FIX First, check the battery charge. Put it on the charger. If it charges, try again. If the problem persists, clean the battery terminals on the tool and the battery with a dry cloth. Look for dirt or debris. Re-seat the battery firmly until it clicks.
IF THAT DIDN'T WORK The trigger switch or motor brushes may be worn out. For the XSH03Z, the switch assembly or brush holder assembly would need replacement. This requires disassembly.
HEADS UP Before any disassembly, remove the battery. Never probe electrical contacts with metal tools while the battery is attached.