New (Used) Sym Citycom 300i battery issues

[cavenger]

So I just got this scooter the other day. It had been sitting for at least 4 months. The first day I looked at it, it wouldn't start, so we jumped it. I took it for a spin and bought it the next day. However, I couldn't get it to start again when I started to put it on the trailer, so I figured the battery was having issues.

Last night I put the battery on a charger for a bit and then put it and the scooter started right up. I left the battery in the scooter because I felt like i had ridden long enough for it to have charged.

Woke up this morning and it wouldn't start again. So I took it to Auto parts store and they tested it and said that it was good but it just needed a charge. Any advice?

Thank you! - Newbie.