Good day andebri,
Welcome to the RobotShop forum.
Error 5 is a charging error. Please make sure your charging contacts on the home base and on the underside of your Roomba are clean. You may also want to confirm that the battery is properly installed and that the bottom cover isn't loose in any way.
If the problem persists and your robot is still under warranty, we recommend contacting the distributor where you purchased it, or the manufacturer, iRobot, directly. iRobot's # is 877-855-8593.
Otherwise, we can always diagnose it for repairs. The details of our repair service can be found here
If you have any questions, don't be shy; let us know.