iRobot Roomba Authentic Replacement Parts - Roomba Integrated Dock Charger with North American Line Cord - Compatible with Roomba 500 600 700 800 900 Series Robots - 4452369 , Black: Amazon.com: Industrial & Scientific
Roomba 551 Troubleshooting - iFixit
Charging error 3 fix on my $50 Roomba 560 - YouTube