First, clean the charging contacts on the Roomba and Home Base. It will help your Roomba connect with the home base correctly.
Your Roomba will not charge if you plug it into a faulty power outlet. Try plugging your Roomba into another outlet.
Sometimes, the battery in your Roomba may be displaced from its original position for a variety of reasons. So, check it and if it is, reposition it.
Resetting is always a good solution for a Roomba when it starts to misbehave. It will revert your device to its factory settings and resolve any software-related error..
If nothing works, contact iRobot customer care. They will help you fix the problem.