Even if the battery is not charged, that does not mean it is bad (although it's not real good for them to get completely discharged). You may have a problem with your trickle charger or a connection. Once again a voltmeter is almost necessary to diagnose this correctly. If you don't have one, find a friend that does and knows how to use it. It will save you a lot of time and probably some money because you won't be buying parts you don't need.