Step 1: If there is room, place the battery on the surface next to your Assistant Tank. If there isn’t room, you will need to lift the Assistant Tank and place the battery underneath it before continuing to the next step.Step 2: Carefully lift the Assistant Tank and place it on top of your battery. Be sure to line up the Unlocked Icon with the line on the battery to make the next step easier. The bottom of the Tank should allow it to sit somewhat snugly in the top opening of the battery.Step 3: Slowly rotate the Assistant Tank until the Locked Icon lines up with the line on the battery and you hear/feel the unit lock. It may be easier to rotate the Assistant Tank while holding the battery steady. The LEDs will turn on when properly assembled.Tip: It may be easier to replace or remove a battery when your Assistant Tank is empty.