If the 2009 scooter has the original battery, it is probably worn out. Batteries last 3 to 5 yrs.
To test it, charge it fully and take to an auto parts store that will test the battery under load (usually free service).
To charge it, you will need a low current (less than 2 amp) charger. Most owners buy a battery maintainer which can do the charging and keep the battery charged during low usage months (winter). A basic Schumacher maintainer at Wal Mart is $20.
Sears often has them on sale for the same price. Harbor Freight sells one even cheaper.
The maintainer comes with a pigtail that you permanently attach to the battery terminals. Then there is a 2 wire connector that connects to the maintainer. So it can be easily attached and detached.
The clicking sound that you hear is probably the starter relay being brought to the ON position, but the battery does not have the capacity to actually energize the starter motor. If the battery is good or with a good replacement battery, you continue to have the same problem, then there are other places to look, but an old tired battery is the most likely.
Scoot safely,