Hi Im sorry to hear that. I am a robotics expert with over 20 years in the field hands on repair. This is just a failing battery is all.
These will fail at different times depending on use and recharge times. In other words its best to let then run down as much as possible before letting it recharge. That will increase the life of the battery. Unfortunately this one sounds like it needs to be replaced.
You can do that easily and I will help you all the y with this easy step.
The best place to get a replacement battery is Best Buy, or Batteries Plus+.
You can also order one from iRobot:http://store.irobot.com/
I will stick with you until this is complete.
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