Roomba 415 Battery Teardown

Purchase a small triangle file $1 fr hardware store

Compare if fits snugly into the triangle screw head

Unscrew normally. Can use a plier to increase the torque as it can be quite tight

Refer to another Instructables for changing out the defective cell inside the battery pack.
www.instructables.com/id/iRobot-Dead-Battery-Cell-Fix/