DPI brand charger or flat light-weight yamaha charger?(either one could be factory correct. i think that the batterys may be messed up from sitting dead so long, the charger is trying to figure out why the batterys are acting so funny. i think if you let that process continue, it will charge the batterys. the batts probably dont have much capacity or run time right now. you will have to do several charge-discharge (Drive it) cycles to see what capacity can be restored to the batterys. Hate to break it to you, but allowing the batterys to go that dead and sit dead has voided the battery warranty. yamaha warranty states that the batterys can never be allowed to sit at a state of charge lower than 80% discharged. if you are going to leave your cart for a long time, you MUST have someone maintain your cart batterys while you are gone (charge them about every 3 weeks, water them as needed, and drive it around the block to excersise them, sounds funny but it will pay off with less hassles like these). even if the charger says it will take care of them while you are gone, it cant water them for you when they need it. we can tell when batterys have been mistreated by comparing the miles and amp-hours on the controller to the battery health determined by a discharge test.
Buy a Factory service manual for your cart, you will NEVER regret it!