It sounds like the batteries have gone bad and need to be replaced.

The batteries contain a gel that needs to have current run through it on a regular basis (at least 8 hours once a week) or it will solidify. If you attach the charger, what will most likely happen is the green light will either stay green or go to green after a very short time. When you turn on the power chair, nothing happens. The charger will indicate the batteries are full, but instead of being full of pwer, they are full of crud. Your warranty will most likely not cover replacment as this is due to customer neglect, but your insurance may still cover the replacement if you can wait for the process to go through. Otherwise, you will need to replace the batteries on your own. Good luck!